This is great! It demonstrates a genuinely a better understanding of the non-linear structure of Metroidvanias than a lot of games that claim that genre and sell well. The map construction is great even besides that.
If this had sound it would be incredible. As a minor aside, if you want to put audio feedback in games but don't have time to make the sounds, an indie dev created a little program that randomly writes sound effects for just that purpose. Look up "rsfx"
I kind of wish that after the boss you could do a new game +, since I apparently missed one of the charms.