In case people starting out with the game and, like me, were struggling with the first levels at first, be sure to check the shop menu and stock up on overrides, mainly HP ones, it's almost necessary to stock up as you're getting used to the jank combat because of how relentless the spawns can get and due to how some enemies have attacks with insanely short visual queues, you will likely get hit quite a bit in certain points.
Maintaining HP overrides after each level should make unlocking everything in the normal levels much easier.
Side note, did the bell minigame, Current best is around the 7k mark so it's definitely not as brutal as I expected it to be. You just need to figure out the lowest the green bar goes so you know where to look after every hit in case it's placed there in the next one. It is a pain to have to go back if you slip up even once but the minigame is pretty short for something where you have to endure getting hit 108 times so it doesn't take TOO long to get back to where you were.
Edit: I did it in the run I did RIGHT after posting that side note. All things considered, it was pretty easy!