Hi,
am I the only one whose friends from the other platforms (Steam, Uplay, Xbox) are not visible? Because this is one of the main things why I wanted to use GOG Galaxy 2.0.

I've wondered this myself. Pretty much the only reason I leave Steam open all the time is so I can still chat with my main pal over there, so it'd be nice to finally have friends lists and chat fully integrated here.

Not integrated as of yet, but it is in the roadmap.