Versions bought outside Steam have no access to Steam services. The closest you can get is manually adding the game to Steam, and it would account for the hours spent in it and let you use Steam Input, which is completely local.
But in many cases, it is the same product because things like online gaming don’t go through Steam servers other than perhaps serving the Steam friend list, e.g. BG3 online coop works across GOG, Steam, and consoles, and obviously the servers aren’t hosted by Steam.
Versions bought outside Steam have no access to Steam services. The closest you can get is manually adding the game to Steam, and it would account for the hours spent in it and let you use Steam Input, which is completely local.
But in many cases, it is the same product because things like online gaming don’t go through Steam servers other than perhaps serving the Steam friend list, e.g. BG3 online coop works across GOG, Steam, and consoles, and obviously the servers aren’t hosted by Steam.