Honestly, I don't know. Time is a limited commodity right now.
There are several ways to approach this task. An Arduino device with an old RC radio gimbal talking ModBus might be one.
Second, from what I now Mach 3 plugins were plain DLLs. Mach4 plugins seem to be something else with reference to the .M4PW file type. If however, this is a DLL in "disguise", it doesn't really matter what language it is written in as long as you can output a DLL as project target. I'm quite proficient in the Delphi RAD development platform and it's possible to develope DLLs on this. What this will take is some sort of Mach4 SDK and a GamePad VCL Component, all which I know little about at the moment.
As a hobbyist, a gamepad is a device that almost everyone has lying around somewhere and it's excellent for jogging purpose being able to keep a close eye on the machine while moving around.
Thom