The TMC4671 (https://www.trinamic.com/products/integrated-circuits/details/tmc4671/) can support steppers, Three-Phase, and DC motors/voice coils all running closed loop with Field Oriented Control for steppers and three phase motors.
Having an expansion board running one or more of these of these drivers with a power stage of 4 half bridges would allow maximum flexibility for motors/feedback.
There are dual feedback inputs so you can have one feedback mechanism for commutation and one for the actual position loop. They support both incremental ABN encoders, Hall sensors, and BISS-C/SSI encoders.
This would allow you to drive essentially any motor in step/direction mode from a duet.
Sweet tiny extruder with a micro geared dc motor for the smallest direct drive possible (https://www.pololu.com/product/3055)? You got It!
Drive a linear motor for the absolute fastest speeds for benchy printing? You can do it!
Motor torque feedback for extruder pushing force tracking and grinding prevention? Totally doable.
Want to drive a voice coil optical stage that you got on ebay just because? Easy.
Got your hands on some optical scales from a CNC and never want to use limit switches again? Sure.
That's a lot of functionality for a 12USD chip...