>Lots of games (specifically indie games) have no DRM at all, you can freely copy to some other storage and play it later.

I doubt your "lots" claim, it is ambiguous, do you maybe mean a very few ? I found this >Total number of DRM-free games: 1,075 out of 41,147 games in total.

This is my source, if it is wrong let me know https://www.pcgamingwiki.com/wiki/List_of_DRM-free_games_on_...

At least Valve games seem to be DRM free