My idea for this is that the player would only be able to touch the starting surface and not touch the ground until the screen is cleared (the only exceptions would be touching a spring or landing during a cutscene). If they touch the ground in any other circumstance, they would have to restart immediately.

Are there any holes or impossibilities in my idea that you know of?

You should probably do a run or even a TAS of it first, and also this would be more appropriate in the category extensions fourm. Perhaps a category like that which would make more sense is grabbing the first berry in each level and not collecting it until the end of the level, this is problematic with old site, reflection, and summit. With summit it could be the first berry for each section, old site could be until awake, and reflection would just be normal reflection I guess.

But collecting the first berry in each level and carrying it to the end means you shouldn't die which will make it more difficult

Grabbing a berry doesn't mean you can't touch the ground, heck you can do an extended hyper with a berry and not lose it. Also groundless is a thing, but I don't think anybody routed it out completely.

was gonna say that myself, the berry thing. but thinking about it there is already a category for that...

I know I'm late but I'll try I run to see how possible it is, obviously prologue doesn't count otherwise it'll be impossible for sure. I will try any% and if an a side isn't possible then I'll try to see if I can grab the casette tape and beat the b side.