Regrettably I can’t find a feature which goes into depth about the custom software itself, but gestural music making has allowed guitar legend Jason Becker to continue making music despite tragically and famously suffering from early onset ALS.
He’s able to transcribe music, note by note, with the assistance of a computer and special software designed in part using a communication system made up of eye movements which his father helped develop and programmed by a family friend software engineer.
I mentioned this briefly in the do companies take disability access into account thread as well, but it’s really inspiring and shows that gestural music making is more than just theremins and light sensors etc.