There have been various efforts along these lines so as you can see it has and can be done…
MIDI-UI
But there’s lots and lots to do. The basic 4 knob device is still evolving and obvious the core development is based around the zynthian kits as this the basic structure around which everything else evolves. (Just look at the debate that grows around a Sustain Pedal 
)
It’s like a lot of things, the more effort and justified opinion goes in the more stuff comes out, so do investigate the possibility of investigating yourself as that way you will be able to refine your own requirements. I’ve often found that without that element of responsibility from the requester it’s very easy for them just to let imagination run wild and increase demands till everything just becomes unreasonable and nothing gets finished.
If you can define your own requirements then we get a User Story that is easy to mix into the overall demands. But certainly examine the link above and see how it matches your ideas and expectations.