You can invite players from different devices, you can message with them and make a team with them. Why is there no way to add them as a friend?
I met many people who were playing on PC that were giving me advices, but that was it. No way to continue to play with them if you didn't play with them recently or you don't remember their nickname.
Is it not possible to have at the very least a cross play friend list (not even asking for cross play clans) before the cross save?