Ok, so I think I might go a DIY route with this. I realize that with the grid/arc, I have binary and (knob-based) continuous stuff covered, so no need to double-down on any of that kind of stuff. So having something that focuses exclusively on funky controls would be the way to go.
At the moment I’m thinking something that’s arc4 sized, but that might be a needlessly compact restriction. Either way I’m thinking the width of the newschool grid/arc, so it would fit well in that setup.
I’ve not done this kind of touch stuff before in Arduino-land, but I’m imagining (hoping) it’s not too difficult or different from regular analog-y reading stuff.
With this many continuous inputs I may consider going HID instead of MIDI since I’d want to have higher resolution outputs from the continuous stuff, and it would swallow up a huge amount of CCs if everything is doubled up with MSB/LSB. (But at the same time, HID wouldn’t allow LED feedback, so there’s that too)
So here’s a quick sketch:
On the left would be some piezo-based barres (ala ciat-lonbarde Tetrax):
Then some Manta/Rene/PressurePoints-like ‘touch’ pads (where pressure = skin conductivity), with possible backlighting/LED feedback:

Then finally on the right, something like a small array of touch points that would be used to control cross modulation and repatching in software, ala Mocante: