Of course! I used the Steam Flatpak when I used to have Steam (I don't game using it any more), and everything worked exactly as you expected it to.
If you have an nvidia card, you will need to do some manual set up for the drivers (add the non-free repository and sudo apt install nvidia-driver), but it works without a hitch after that.
Debian has a lot of strange misconceptions about it, but it's really just like any other distribution and I'm a big fan of the stable base. I get "update fatigue" from all the other distros.
Yeah, I like it very much myself but because it's always behind it never had the features I need in a home desktop environment. But I might try it again. Thanks for the input.