This is a pretty maintained list, and even if I disagree with the inclusion of some things because all you’re missing is cosmetics, it is pretty easy to argue that “complete game offline” should include all content of that game, so I’m not gonna start a fight about it
https://www.gog.com/forum/general/drm_on_gog_list_of_singleplayer_games_with_drm/page1
This is a pretty maintained list, and even if I disagree with the inclusion of some things because all you’re missing is cosmetics, it is pretty easy to argue that “complete game offline” should include all content of that game, so I’m not gonna start a fight about it