Oh this is an amazing idea for a deckbuilder. I love the band-building aspect, the scope for this could probably go as far as filling a whole orchestra if you wanted it to! And we love choosing 1-of-3 things.
My only feedback would be that initially I didn't realise I needed to use the number keys to play the instrument.
We also made a deckbuilder for the jam, so would love your feedback if you wanted to try it out too!