I always keep list of good ideas to include, so if you have time and skills to do some programming - I'm looking for help.
Simpler but nice to have - add Buzzer functionality - I have footprint/signal routed for a small buzzer - need coding.
Bit more difficult - add Stepper support, in addition to current PWM servo. This has many benefits, but is alot more involving on code and even some HW changes will be required (stepper shield). Stepper motors are nearly indestructible, and some are still out there from prior solutions, where head unit failed.