I agree, their own games play well an are perfect quality an will always be the priority for them which I totally get, I think they must know most people do have another console so it's no big deal to them, really the only games I see struggle are the more realistic ones, the animation type seem fine, but once you go into heavier graphics that's where it starts to cut back on quality to be able to offer the gameNintendo could make their consoles the equivalent of the latest gen if they really wanted to, but they've never really been about that. They make most of their money from their exclusives like Mario, Zelda, Animal Crossing, Pokemon, etc etc. So as long as their consoles are good enough to run those, then they're sorted.
I know they do release third party titles as well, but they're never the main focus. That's why I've got a PS5 and a Switch and will always get the PS5 version of multi platform games.
I agree about screen share - wouldn't be surprised if it's laggy. But then I doubt I'll make much use of it anyway!
I'd like to use screen share just more for fun, am happy it's finally got voice chat because I really could have used that with a few games at times, but if it comes down to having to have screen share off to improve the quality of the chat I'll take the chat over it, I'd rather be able to talk an hear clearly than watch a friend's game