I mean yes… kind of. You can go to your library in gog and download (slowly speed-limited and broken into 4 gb chunks for some damn reason) which means no client needed.

But steam does have games that are DRM free after that first install. Ones that you can copy directly out of the folder and put them anywhere and run. Steam no longer needed.

There is a list here https://www.pcgamingwiki.com/wiki/The_big_list_of_DRM-free_games_on_Steam although it suggests its about 600 games more that arent on the list yet.