Everything can support cross-play, every console/pc with connection to the internet atleast, but its up to the game devs.
If the game was originaly made with steam multiplayer api and they used steam servers, it will take time to port it over to another server platform/api.
But in general, its allways possible to make a game crossplay, but sometimes its not easy/cost-effective to do it. For example, the game engine used might not be compatible woth the desired multiplayer api.
Dont take this as 100%, as i have little experience in game dev.
Latest Answers