Yessss! Love that you've started making this. I've been playing famidash a bit lately and was wishing there was a GB equivalent. It seems every bit as challenging. :)
I was quite surprised when I discovered famidash a few months ago, I'm glad that I'm not the only one trying to have Geometry Dash on a retro console :D
It's a very fun and challenging experience to make! The coding part is pretty much done, now it's about level and music design. And I can tell it could be challenging... for players this time!
I'm not planning any save system right now, my focus is to fit as much things as possible in a 32 kB cartridge (that's the "challenge" I set myself originally, and it helps me to avoid adding too much features). Since there's no save, every level is already unlocked when booting up the game and progress only affects cosmetics. (Also, I have to say that I haven't looked yet at banking or saves at all, but it may come with future projects!)