@t3p3tony Oh gotcha, yeah that was a typo in my question, had been testing with "+". Appreciate your responses!

@pcr With that I get "Unknown pin name 'pin1'"

Also may be relevant, but this is the firmware currently on the board:
RepRapFirmware for Duet 3 MB6HC 3.4.0beta6 (2021-11-06)

Running the LIS3DH accelerometer

Just got it to recognize the accelerometer with C"SPI.CS3+SPI.CS2". Flipped the order on cs3 and cs2.

Re: [Duet 3 mini 5+/6HC] Accelerometer not found on specified port

I am using the wiring specified at this location:
https://duet3d.dozuki.com/Wiki/Accelerometers

Confirmed all wires are connected via multi-meter and to correct locations as specified in the table. Note I am using M955 P0 C"spi.cs2_spi.cs3" instead of the cs3 and cs4.
Per: https://duet3d.dozuki.com/Wiki/Duet_3_Mainboard_6HC_Wiring_Diagram
My duet 3 does not have a cs4 port.

I am connecting directly to the mainboard, no daughterboard.