The idea is awesome and the execution and style is one of the best I've seen so far.
Though it felt the struggle of combining combat with the music timing, if I can advise you could even drop the "combat" and have the notes you play or the streak of timed attack activate world events or interact with instrument npc in a certain puzzle/rythmic way, just my two words I think that adhering to close to the rules of exploration of classic metroid vania for your project may be detrimental. I would love to see your idea fully fledged because everything looked and sounded awesome in what I have played!
The whole baroque theme was so awesome with those clavicembals raging.