What are you talking about? Cross saves work. I don't know about cross play..that would probably be a bit unfair in some games but not all and I imagine anything missing will be added.
Also the pc app(s) have recently been getting better very quickly with constant updates. I've seen 3 in one day. I imagine they are rushing to make everything better by the series x launch. It's gotta be hard with everyone working remote...a console launch is massive, I don't envy Microsoft or sony on that front.
So I think we will see very rapid improvement to the entire eco system and especially the pc and phone apps. In fact the gamepass android app has gone from useless to almost great in 3 months and I imagine they aren't close to finished there either.