I have a guide on how to get a full inventory quickly. You'll have to change it a little bit but you can still do the same type of thing. Also, the quickest way to get maximum points is to get the infinite coins glitch in 4-Castle. Good luck!

Could there be a way to manipulate the goomba in 100%?

Yeah, there would be some RNG but not that much.

It would really be interesting to see someone get 99 of each inventory power-up quickly.