I agree Bill, this makes a lot of sense!
There are a lot of programs that support midi keyboard input, like most DAWs, MuseScore... and the synthesia videogame https://synthesiagame.com/
I've tried playing around with some of them using my instrument plugged in as a midi kb.
But these are huge beasts! I have yet to find a simple beginner dev friendly program...
MuseScore is written in Qt, so I also went to the Qt forum and I posted there asking "Is Qt a good choice for my project?
I fiddled with JS and WebMIDI... I did manage to get my browser to play the notes I inputted from my instrument, but gosh, did I find JS painfully confusing!
Having said that, 2 people encouraged me to dig the js route yesterday...
one on the Qt forum - the only reply there) from a guy who said "you might want to consider js"
and then one person on the löve forum pointed in the exact same direction and even wrote a code sketch for me on p5.js
I guess I'm going to reconsider my position and give JS a second chance...