you can use the noclip command in the console to skip major parts of levels. I don't think this is legal in any% but if wanted to run you could make a separate category for it. I have a video showcasing one of the possibilities here p.s you aren't supposed to fall through the floor that was me.
No-clip is definitely banned in any%, a no clip run would probably be pretty boring imo, but I wouldn't be opposed to adding it if its something people want to run. There are some pretty cool things you can do with no-clip, although spamming the item swap key bind allows you to move really fast backwards while noclipping and would likely make all the interesting stuff useless ¯_(ツ)_/¯
Another thing that needs to be thought about when adding a category is weather or not it is fun, and will people run it. Like Is300, I'm not sure if I personally would find this very fun. There isn't very much challenge.
I think if this category were to be added, only like 2 people max would ever actually play it. It would be the kind of thing where the first person to play it would get a free WR and never touch the category again. And if I am wrong and people actually run the category, everyone will most likely lose interest in it after maybe 3 runs or less. Personally, I'd run it once if I'm really bored and I probably won't run it again after. Also, the camera in noclip sucks so It can get kind of annoying sometimes.