Yeah my first thought was I'm not sure it's your call if you have cross platform communication cdproject lolUnfortunately I don't expect GOG Galaxy to work on Linux any time soon, especially now that they are clearly trying to get a metalauncher working. Cross-platform chat in particular is either an empty promise (well, it's doable with Steam because Valve is nice and all, but all the other platforms are more of a problem), or it will require significant hoop jumping. Orrrr they're doing the taskman trick, but that's insanely platform specific.
Actually, even GOG's Linux installers would benefit from some check up.