Recently on Dying Light they added the feature to play with friends who bought the game on other stores like Epic games or Steam. They did this using a connection through Epic games. Could something like this be added?
To be honest in that case I don't know who hosts the game but it is highly userfriendly and solves the issue for the users who bought the games on different stores.

As someone currently trying to get a dedicated server started for my community that is split across Steam and GOG versions of the game, this is definitely something that sounds good!