Plinky, a PCB-synthPlinky is an 8-voice polyphonic touch synthesiser that specialises in melancholic sounds.
May be interesting from keyboard perspective.
More info and samples at: https://plinkysynth.com/
Plinky feature walkthrough
Published on Tue 8th Jun 2021. Featured in KBD #30 (source).
Music visualization on your keyboard through the Raw HID interface by Ruirize
Jazzkeys is a nice app playing piano sounds while you are typing – created by the Stockholm-based studio Plan8.