That's a very good interpretation of the theme and implementation. Gameplay is great, I liked the overall art and audio.
I feel you kinda need to make the fact that you recharge close to bullets more obvious without reading the description on Itch, cuz those red circle around the bullets are looking like they'll damage you.
It's pretty simple in terms of gameplay - as you're just facing bosses again and again (could be cool to have some waves or things to do between bosses, or some story cutscenes maybe?)
Nice one indeed.