That’s a neat project. It’s an interesting idea.
The only thing I’d note is that few of our users are using that many expression pedals. If they’re using MIDI, the vast majority of our users are commonly using MIDI footswitches to step up and down in a set list to send out program change messages to change all of their pedals to the same patch. Or they’re using CC messages (or program change messages) to activate or bypass something, to launch special modes like the tuner, or to tap in the tempo.
Poly does all that stuff too if you want more traditional control. Over Bluetooth and WiFi too, which can be handy for having controllers at different parts of the stage. You can setup the board to be as many square as you want, so if you want 20 squares to easily jump between songs that’s fine, or bigger buttons for up and own.