Bungie can build whatever they want and implement any features that they want. Whether Sony allows those features to be active on their platform is a different matter. And if Xbox and PC players have cross-play and PS don't, that's just gonna look bad for Sony, which would just be even worse for them considering how much of a stain that already is for them in the consumer's eye. Whatever lights the fire under Sony's butt to finally allow full cross-play is good in my (and almost everyone else's) view.

Again, it’s nothing to do with bungie!!! Sony control cross play, I suggest you go and watch a video? Bungie don’t have to build anything but Sony have to turn it on! Cross plat has been available for years and years but Sony and Microsoft have not wanted to activate it! Mostly Sony as they have the market share! All bungie can do is basically put a business case forward to Sony!

Sony does not control cross-play for the industry, only on their own platform. Most developers just don't want to have to deal with locking only one platform down, most likely from a legal perspective. An example of this is when Fortnite first came out and someone discovered that Xbox and PS were playing each other. Once this was discovered, Sony had Epic disable that feature on their platform and that was "fixed" within a couple hours. What this means is that Epic already had built up cross-play functionality and then implemented it (on accident). That proved beyond any doubt that cross-play was totally possible from a technology standpoint, it just wasn't being allowed on certain platforms by certain people. And the fact that Epic was able to fix by literally just turning it off shows how easy it is to manage it. It's not hard, it's just them being told no by one specific platform, but none of the others. Which is why players on other platforms were playing with each other just fine, even without Sony.

Sony is testing cross play with fortnite.

Right, and they jacked it all up by locking players Epic accounts to their platform and they got trashed by the playerbase and the news media for it. Sony will eventually learn that the players, their customers, want cross-play. There just need to be enough developers that give players the opportunity to push Sony over the edge, and I believe Bungie is capable of doing that.

That was before Sony agreed to test cross play.

No, that's what they did when they agreed to test cross play. It became big news when Fortnite was released on the Switch and a bunch of PS players tried to sign in to Fortnite on the Switch and discovered that PS locked their Epic account to the PS platform. So PS players could play against other people but they couldn't sign in anywhere other than PS. That's how I understood that situation.