I was wondering when someone would ask!
one is a menu option you just need to change (and then can change again)
the other one (probably the most substantial unlockable) is a accessible from the title screen via an invisible path- if you look at the texture on the background starting from the knuckle, you can probably figure it out. There’s no actual in game hint so it’s kind of unfair, so I figured I’d just give it away lol