i went to a unity presentation for polywahteverit'scalled last night and got to ask questions. an apple employee that works on xr was there and i asked him if the package created with unity would have some exposure of the entities in it to xcode, he said it may be possible, it is still new. but then the guy form unity told me this would not be the case, the whole emulation and input would be handled in unity and you would have no control of it in xcode.
i really wish apple would push swift onto engines. godot has a tiny swift community but without apple's direct support it isn't going anywhere. the apple rep told me they are looking for developer input on tools they use and workflows, so speak up.
but yeah, for me i'm still on scenekit. i was looking into porting my game from scenekit to realitykit but hit a roadblock with the new realitykit composer only supporting xrOS. i wanted to build a mac game and xr experience in tandem. the apple guy told me realitykit might support mac in the future, again he iterated that it is very early in development and they didn't want to break things in support for multiple platforms.
i was excited for unity but now i'm looking forward to sticking to apple frameworks and hope they make them more robust.