The Pro and the Studio cant be even close to the same enclosures/housings unless Apple has given up on the Apple Silicon Mac Pro not being expandable. Who knows, maybe they have given up. Apple Silicon’s design isn’t aimed at expandability…which is a good thing considering focusing on expandability would have changed massively Apple Silicon. its design aim is efficiency/high computational power per watt. On that front it’s the biggest success in personal computing history IMHO.
My guess is Mac Pro will need an interesting backplane to be expandable. But I still don’t see how they get a self installed graphics card or user added ram to work at near peak capability with the highly shared nature of the SOC. Doable? I’m sure. Doable that takes full advantage of the user installed extension? I have my doubts.
Either way I don’t see how a Mac Pro interferes with an M2 ultra being put in the small Mac Studio enclosure.