So after you posted this I played the game a little and you were NOT kidding when you said the final levels were hard. My god.
Anyway, to make the difficulty more sensible the enemies now increase their speed after every round, so the first rounds are easier but you're almost certain to use a powerup in the last. I think this change fits the game well and the difficulty curve should be a lot more reasonable now (I actually beat the game for the first time ever lol)
Also the audio is actually fixed now!!!! If it decides to break again I will have problems (no I won't but I will feel sad)
There's a couple smaller changes as well, but I hope this is the last time we need to release small bugfixes to the game.
It's 2 am right now and I'm only writing this because I am so used to the jam sleeping schedule by now that my body is not allowing me to return to normal and mid sleep I got up from bed and onto the computer to write the devlog and this comment.
In conclusion, the game is now verifiably "completable", go check it out and if there's anything else you're welcome to post another reply to this ever increasing chain lol