In their official FAQ
Fantasy Strike, a newly released fighter for the PC, Switch, and PS4 platforms, will not have full cross-play capabilities. According to the dev, that’s not their problem, but Sony’s.
While many smaller studios have expressed their disappointment with Sony’s cross-play policy (or lack thereof, unless you’re a huge publisher like Epic Games or Activision), Fantasy Strike developerSirlin Games is embracing it. In addition to publishing a damning infographic, the studio has also made the game’s cross-play shortcomings crystal clear.
The official FAQ states that PS4 owners “Can play with Steam players (but not Switch players, as per Sony’s restriction,” and “When you create a FantasyTag [cross-account] on PlayStation 4, you do not create a password, because Sony does not allow account data from other platforms to be used on PlayStation 4, and it does not allow your PlayStation 4 account data to be used on other platforms either.” So not only can you not use cross-play with the entire ecosystem, you can’t keep your data either!
Will that change? Possibly, but for now Sirlin isn’t hopeful: “The only limitation on these things is Sony’s approval. If Sony changes their mind on these things, we will be happy and eager to support them. At this time, we are not allowed to do them though.”
But remember, “PlayStation is the best place to play!”
Cross-platform play [Fantasy Strike]