I looked all over youtube and I could not find the answer. Is this possible? Or the reason why there are other categories means that this is impossible. Can someone find a way to get past the gate into corona mountain and beat the game quicker?

It's possible to clip into the entrance to Corona, but the loading zone isn't there until the flood so it doesn't give you anything.

The other categories would exist either way, but the fact that the any% WR is still over an hour long is a pretty good indication that we don't have an instant shortcut to the end

You can beat the game with 0 stars, as long as you don't bonk. Bonking creates a star particle effects. You do still need to get all the shadow mario shines though.