Proton supports around 15.000 games [0], I couldn't find a concrete number for all games on Switch, but this list [1] has around 4.000 of them.
[1] https://en.wikipedia.org/wiki/List_of_Nintendo_Switch_games_...
[1] https://en.wikipedia.org/wiki/List_of_Nintendo_Switch_games_...
I installed Steam on Debian sid via Flathub / Flatpak, and then installed https://github.com/GloriousEggroll/proton-ge-custom using their flatpak instructions as well.
Honestly, it has never been easier to get a version of proton that makes gaming on linux seamless. Of course, I understand "run these terminal commands" is the usual defensive linux nerd^H^H^H^H coward's reaction, but installing Steam and this package from flatpak and then going from there is a _vast_ improvement from yester-years. I've been fairly happy with it, and I didn't have to do any actual compiling / building!