Hey! This is great! It's hard to provide critical feedback on something like this. Let's start with what I love.
Excellent use of metal music, this is best excellence in sound design I've played so far. The polish/juice factor on this game is amazing. The weapons feel really punchy and everything feels snappy and tight. You must like games such as Celeste or TowerFall? The tutorial is really good too. The upgrade path is sticky enough that I had to force myself not to go for one more round, so I could move onto other stuff.
As for critical feedback, once I realized that the zones could be destroyed, the game started clicking more. I sort of wished that they could be dismissed a bit easier. I think maybe you anticipated players might use these intentionally to their benefit sometimes, but only semi-intentionally did that once in my playthrough, and spent most of my time dismissing them. Perhaps if they could be dismissed with 3-4 bullets on average instead of 5, I would much prefer that.
You should be extremely proud!