Multiplayer between two different apps

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Hi everyone,

I am a Photon newbie, so I'm sorry if the question is dumb.

I am in a situation in which I should make two different Unity applications communicate. One of the two already has multiplayer capabilities through Photon PUN and was built using Unity 2018.4.

The new one has been built on Unity 2021.3 and still has no Photon in it. The necessity is to have the old application and the new one share some objects present in the scene.

The problem (?) is that I am talking abot two different code bases with not much in common, beside the usage of the same Azure Remote Storage / Remote Rendering. The objects to share should be the ones coming from Remote Rendering.

Starting from the assumption that the two apps must remain separate (both for technical reasons and development time) is there a way communication between the two is achievable?

Thanks!