Love this, thanks for your writeup and for telling the world about it!

I got the opentheremin v3 a few years ago, flashed the firmware to make it output MIDI (so I can play virtually any instrument sound with a theremin interface), connected it to an FM synth Pure Data patch, and send all this to my homemade DAW-less setup, including some effects to make it more fun :)

I do intend to use an expression pedal with it too. I once tried using a pedal to kind of autotune the theremin occasionally - which defeats the theremin’s purpose, I know 😆 but it was a fun experiment!

I then also found an open-source Raspberry-based saxophone ! Currently on the lookout for an open-source MPE controller, maybe Exquis…

No screen captures AFAIK (although it might be doable with a custom watcher), but maybe https://activitywatch.net/ can help.