But that’s not the case from the games I’ve played unless you’re getting into hypotheticals.
I’ve played on Xbox live with my cousins on steam in F1 2020, age of empires, gta 4, halo.
The only friction is initial invites from the specific platform but once we’ve played in the same server, it’s very easy to send in-game invites.
As for the issues with virtualization, it’s an understandable issue with concerns around cheating in pc multiplayer games. COD4 was absolutely ruined because of it. Virtualization isn’t very widespread but I’m sure they’ll be more accommodative soon as WSL and Android ship by default on Windows.