I have not been on the forum for a while but I am not sure where else to find fellow chromatic button accordionist.
I have been designing / prototyping a MIDI controller and synth with a C-system layout. It could also be easily (software) swapped for B-system. I have all of the code and CAD drawings online for free but if anyone is interested I might do a manufacturing run.
The sounds are really simple so far but it does have some cool features, like a joystick that can bend the pitch of one note or all of them at the same time.