It seems that Bungie want to intensively enter the cross-play in Destiny 2 but apparently this is not possible, therefore it is a feature that may be introduced in the future.
With the official announcement of the presence of the possibility to carry out the cross-save in Destiny 2, which is to transfer the saves from one version to another, it is natural to think of the next arrival is also cross-play is complete, but this is not yet possible, it seems. The cross-play, understood as the ability to play multiplayer between all the platforms on which Destiny 2 is available and transfer your account from one to the other, is a thing that affects very Bungie, which, however, seems to have other things to think about before they can go to that technical feature.
“Stadia as a platform does not make it more difficult to implement cross-play”, explained Mark Noseworthy of Bungie who wondered if the lack of this feature was due to the insertion of the Rod between the versions of the game. “We are focused on the cross-save this year on all platforms, cross-play is a thing of which we are very interested to do, but we have a lot of other things to deal with before. The question of cross-play for Destiny 2 has been at the center of various rumors, including the one that he wanted Sony and opposite to this the functionality that was desired by Bungie.
Stadia as a platform doesn’t make implementing Cross Play any harder actually. We’re focused on Cross Save this year (for all platforms). Cross Play is absolutely something we’re interested in doing some day, but we have a lot on our plate to chew through first!
— Mark Noseworthy (@knowsworthy) June 11, 2019