I just noticed that any% was just getting all 42 endings, not beating the final boss. I was very interested in something like this and wondering if it could be a thing? Though to be fair any% is already pretty long

Would you prefer that for Category Extensions (when released) or in this current site?

current site if possible. Also thanks for responding so quickly!

Is the final boss referring to Mario?

No, not mario. If you get every ending you can go into the secret room, and then fight Vector, and if you got cursed you also have to fight Garfield after that.