I appreciate all the feedback, I have been thinking about this and going to scrap the idea and take a stab at a configuration plugin. The deeper I get the more problems I am seeing with using GCode and being a sr. frontend Vue developer I should be able to tackle this.
Stay tuned 
I have not tested many boards, I am very early into this project so I will have to keep that in mind. I was planning on having a machine type gcode /sys/machine/cartesian.g that would create all the global variables and then those values would be set with conditional Gcode. Would prevent creating unnecessary variables but without knowing what that limit is... guess I need to do some more research!
I do not see a way to unset variables so I might have to be more strict with the use of local vs global variables. Hummm....
I have been following RRF for sometime and decided to take the plunge and had some difficulties converting from Marlin. In my research I stumbled across the GCode Meta commands wiki and thought this would be a great opportunity to learn something new.
I have started creating a Configuration.g which will allow for a user to simply port over values from Marlin and have a similar printing experience. Right now I am focusing on cartesian support with a bltouch to see if this project is feasible.
If anyone has ideas, resources or advice for debugging I would greatly appreciate it.
Repo: https://github.com/brewpirate/marlin-rrf/
Configuration.g
;===========================================================================
;============================= Getting Started =============================
;===========================================================================
global CUSTOM_MACHINE_NAME = "Ender 3"
;===========================================================================
;============================= Thermal Settings ============================
;===========================================================================
; @see https://duet3d.dozuki.com/Wiki/M308
;
; Options
; ---------------------
; thermistor
; pt1000
; rtd-max31865
; thermocouple-max31855
; thermocouple-max31856
; linear-analog
; dht21
; dht22
; dhthumidity
; current-loop-pyro
; drivers
; mcu-temp
; drivers-duex
global TEMP_SENSOR_0 = "thermistor"
global TEMP_SENSOR_BED = "thermistor"
global HEATER_0_MAXTEMP = 275
global BED_MAXTEMP = 150
; PID Hotend
; ---------------------
;global PIDTEMP = true
;global BANG_MAX 255
;global PID_K1 0.95
;global DEFAULT_Kp_LIST { 22.20, 22.20 }
;global DEFAULT_Ki_LIST { 1.08, 1.08 }
;global DEFAULT_Kd_LIST { 114.00, 114.00 }
; PID Bed Heating
; ---------------------
;global PIDTEMPBED
;global MAX_BED_POWER 255
;global DEFAULT_bedKp 10.00
;global DEFAULT_bedKi .023
;global DEFAULT_bedKd 305.4
;===========================================================================
;============================== Endstop Settings ===========================
;===========================================================================
; Specify here all the endstop connectors that are connected to any endstop or probe.
; Almost all printers will be using one per axis. Probes will use one or more of the
; extra connectors. Leave undefined any used for non-endstop and non-probe purposes.
global USE_XMIN_PLUG = true
global USE_YMIN_PLUG = true
global USE_ZMIN_PLUG = true
;global USE_XMAX_PLUG = true
;global SE_YMAX_PLUG = true
;global USE_ZMAX_PLUG = true
; Mechanical endstop with COM to ground and NC to Signal uses "false" here (most common setup).
;global X_MIN_ENDSTOP_INVERTING = true ; Set to true to invert the logic of the endstop.
;global Y_MIN_ENDSTOP_INVERTING = true ; Set to true to invert the logic of the endstop.
;global Z_MIN_ENDSTOP_INVERTING = true ; Set to true to invert the logic of the endstop.
;global X_MAX_ENDSTOP_INVERTING = true ; Set to true to invert the logic of the endstop.
;global Y_MAX_ENDSTOP_INVERTING = true ; Set to true to invert the logic of the endstop.
;global Z_MAX_ENDSTOP_INVERTING = true ; Set to true to invert the logic of the endstop.
;===========================================================================
;============================= Mechanical Settings =========================
;===========================================================================
;=============================================================================
;============================== Movement Settings ============================
;=============================================================================
;globalDEFAULT_AXIS_STEPS_PER_UNIT { 80, 80, 400, 500 }
;global DEFAULT_MAX_FEEDRATE { 300, 300, 5, 25 }
;global MAX_FEEDRATE_EDIT_VALUES { 600, 600, 10, 50 }
;global DEFAULT_MAX_ACCELERATION { 3000, 3000, 100, 10000 }
; X Axis
; ---------------------
global X_MAX_CURRENT = 800
global X_MICROSTEPS = 16
global X_STEPS_PER_MM = 80.00
global X_MAX_SPEED = 9000.00
global X_MAX_SPEED_CHANGE = 1200.00
global X_ACCELERATION = 500.00
;global INVERT_X_DIR = false
; Y Axis
; ---------------------
global Y_MAX_CURRENT = 800
global Y_MICROSTEPS = 16
global Y_STEPS_PER_MM = 80.00
global Y_MAX_SPEED = 9000.00
global Y_MAX_SPEED_CHANGE = 1200.00
global Y_ACCELERATION = 500.00
;global INVERT_Y_DIR = false
; Z Axis
; ---------------------
global Z_MAX_CURRENT = 800
global Z_MICROSTEPS = 16
global Z_STEPS_PER_MM = 400.00
global Z_MAX_SPEED = 180.00
global Z_MAX_SPEED_CHANGE = 24.00
global Z_ACCELERATION = 100.00
;global INVERT_Z_DIR = false
; Extruder
; ---------------------
global E0_MAX_CURRENT = 800
global E0_MICROSTEPS = 16
global E0_STEPS_PER_MM = 93.00
global E0_MAX_SPEED = 6000.00
global E0_MAX_SPEED_CHANGE = 300.00
global E0_ACCELERATION = 5000.00
;global INVERT_E0_DIR = false
; Jerk
; ---------------------
;global DEFAULT_XJERK 10.0
;global DEFAULT_YJERK 10.0
;global DEFAULT_ZJERK 0.3
;===========================================================================
;============================= Z Probe Options =============================
;===========================================================================
;/**
; * Probe Type
; *
; * Allen Key Probes, Servo Probes, Z-Sled Probes, FIX_MOUNTED_PROBE, etc.
; * Activate one of these to use Auto Bed Leveling below.
; */
;**
; * The BLTouch probe uses a Hall effect sensor and emulates a servo.
; */
;global BLTOUCH
;**
; * Nozzle-to-Probe offsets { X, Y, Z }
; *
; * X and Y offset
; * Use a caliper or ruler to measure the distance from the tip of
; * the Nozzle to the center-point of the Probe in the X and Y axes.
; *
; * Z offset
; * - For the Z offset use your best known value and adjust at runtime.
; * - Common probes trigger below the nozzle and have negative values for Z offset.
; * - Probes triggering above the nozzle height are uncommon but do exist. When using
; * probes such as this, carefully set Z_CLEARANCE_DEPLOY_PROBE and Z_CLEARANCE_BETWEEN_PROBES
; * to avoid collisions during probing.
; *
; * Tune and Adjust
; * - Probe Offsets can be tuned at runtime with 'M851', LCD menus, babystepping, etc.
; * - PROBE_OFFSET_WIZARD (configuration_adv.h) can be used for setting the Z offset.
; *
; * Assuming the typical work area orientation:
; * - Probe to RIGHT of the Nozzle has a Positive X offset
; * - Probe to LEFT of the Nozzle has a Negative X offset
; * - Probe in BACK of the Nozzle has a Positive Y offset
; * - Probe in FRONT of the Nozzle has a Negative Y offset
; *
; *
; * +-- BACK ---+
; * | [+] |
; * L | 1 | R <-- Example "1" (right+, back+)
; * E | 2 | I <-- Example "2" ( left-, back+)
; * F |[-] N [+]| G <-- Nozzle
; * T | 3 | H <-- Example "3" (right+, front-)
; * | 4 | T <-- Example "4" ( left-, front-)
; * | [-] |
; * O-- FRONT --+
; */
;global NOZZLE_TO_PROBE_OFFSET { 10, 10, 0 }
; Most probes should stay away from the edges of the bed, but
; with NOZZLE_AS_PROBE this can be negative for a wider probing area.
;global PROBING_MARGIN 10
; X and Y axis travel speed (mm/min) between probes
;global XY_PROBE_FEEDRATE (133*60)
; Feedrate (mm/min) for the first approach when double-probing (MULTIPLE_PROBING == 2)
;globalZ_PROBE_FEEDRATE_FAST (4*60)
; Feedrate (mm/min) for the "accurate" probe of each point
;global Z_PROBE_FEEDRATE_SLOW (Z_PROBE_FEEDRATE_FAST / 2)
; The size of the printable area
global X_BED_SIZE = 235
global Y_BED_SIZE = 235
; Travel limits (mm) after homing, corresponding to endstop positions.
global X_MIN_POS = 0
global Y_MIN_POS = 0
global Z_MIN_POS = 0
global Z_MAX_POS = 260
config.g
; Configuration file for Duet Maestro (firmware version 3.3)
; executed by the firmware on start-up
;
; generated by RepRapFirmware Configuration Tool v3.3.10 on Wed Feb 23 2022 07:28:14 GMT-0800 (Pacific Standard Time)
; Load Configuration
M98 P"Configuration.g"
; General preferences
G90 ; send absolute coordinates...
M83 ; ...but relative extruder moves
M550 P{global.CUSTOM_MACHINE_NAME} ; set printer name
; Network
M98 P"modules/network.g"
; Drives
M98 P"modules/drives.g"
; Axis Limits
M208 X{global.X_MIN_POS} Y{global.Y_MIN_POS} Z{global.Z_MIN_POS} S1 ; set axis minima
M208 X{global.X_BED_SIZE} Y{global.Y_BED_SIZE} Z{global.Z_MAX_POS} S0 ; set axis maxima
; Endstops
M98 P"modules/endstops.g"
; Z-Probe
M98 P"modules/zprobe.g"
; Heaters
M98 P"modules/thermal.g"
; Fans
M98 P"modules/fans.g"
; Tools
M98 P"modules/tools.g"
; Custom settings are not defined
; Miscellaneous
M501 ; load saved parameters from non-volatile memory
M911 S10 R11 P"M913 X0 Y0 G91 M83 G1 Z3 E-5 F1000" ; set voltage thresholds and actions to run on power loss
/sys/modules/endstops.g
; Declare base pin names for endstops
var X_MIN_PIN_BASE = "xstop"
var Y_MIN_PIN_BASE = "ystop"
var Z_MIN_PIN_BASE = "zstop"
var X_MAX_PIN_BASE = "xstop"
var Y_MAX_PIN_BASE = "ystop"
var Z_MAX_PIN_BASE = "zstop"
; X
if exists(global.USE_XMIN_PLUG)
var X_MIN_PIN = {exists(global.X_MIN_ENDSTOP_INVERTING) ? ("!" ^ var.X_MIN_PIN_BASE) : var.X_MIN_PIN_BASE}
M574 X1 S1 P{var.X_MIN_PIN}
if exists(global.USE_XMAX_PLUG)
var X_MAX_PIN = {exists(global.X_MAX_ENDSTOP_INVERTING) ? ("!" ^ var.X_MAX_PIN_BASE) : var.X_MAX_PIN_BASE}
M574 X2 S1 P{var.X_MAX_PIN}
; Y
if exists(global.USE_YMIN_PLUG)
var Y_MIN_PIN = {exists(global.Y_MIN_ENDSTOP_INVERTING) ? ("!" ^ var.Y_MIN_PIN_BASE) : var.Y_MIN_PIN_BASE}
M574 Y1 S1 P{var.Y_MIN_PIN}
if exists(global.USE_YMAX_PLUG)
var Y_MAX_PIN = {exists(global.Y_MAX_ENDSTOP_INVERTING) ? ("!" ^ var.Y_MAX_PIN_BASE) : var.Y_MAX_PIN_BASE}
M574 Y2 S1 P{var.Y_MAX_PIN}
; Z
if exists(global.USE_ZMIN_PLUG)
var Z_MIN_PIN = {exists(global.Z_MIN_ENDSTOP_INVERTING) ? ("!" ^ var.Z_MIN_PIN_BASE) : var.Z_MIN_PIN_BASE}
M574 Z1 S1 P{var.Z_MIN_PIN}
if exists(global.USE_ZMAX_PLUG)
var Z_MAX_PIN = {exists(global.Z_MAX_ENDSTOP_INVERTING) ? ("!" ^ var.Z_MAX_PIN_BASE) : var.Z_MAX_PIN_BASE}
M574 Z2 S1 P{var.Z_MAX_PIN}