i don’t think my controllers are the answer, if i’m understanding what you want to do. you want to build a device to specifically control one instrument, and mine speak directly to live. they will have generic midi control as well, but they’re not worth building if you’re not using them for the intended purpose.
i think you just want a custom controller. i’m not sure which apps that are available fit your needs, if any. so you may have to code something for yourself. for hardware, just check the modules at http://ucapps.de. dout is for leds, din for switches, ain for pots, etc.
i would look through the existing apps and see if anything fits your needs. there’s probably one that uses ain and dout at the same time, with notes that are reconfigurable. i don’t know much about the existing apps because i code my own.
writing something like this on your own is pretty basic, and there are plenty of code examples available.