Honestly what's the point in having it? Heroic is already a better option. GOG Galaxy is a simple launcher, if they port it to Linux then it would also need to be a Wine/Proton prefix manager. Its not a massive amount of work, especially since umu-launcher exists now, but its just pointless effort IMO. Unless they're willing to invest the same amount of work into it that has gone into Heroic and Lutris, it'll just end up being the inferior option.