Basically what the question asks. I installed Gwent on Steam and have been playing for a while. However, I just purchased Thronebreaker on GOG. Will I get the bonuses? Is there anything special I need to do? Also, can I install by an offline file, or do I have to install through Galaxy? Thanks to anyone who takes the time to help.

Unfortunately, no, I don't think you get them that way. I believe they both have to be on GOG. However, if I'm wrong, feel free to correct me.