How are controllers with Proton?

I don't own any controllers.

I started playing Dark Souls 3 which I now understand has a controller strongly recommended. I may as well just look into getting a controller of some kind as I have a few games that have somewhat janky kbm controls and are better enjoyed with a controller.

I just wanted to ask for general advice about what controller to get in terms of compatibility. Also if someone has made a controller that's more in the spirit of foss that also works fine with Steam and Proton games that would be nice?

I know Steam is pretty good with Playstation controllers and I used to use a PS controller (don't remember what generation) with some native Linux Steam games, not sure how the whole PS vs Xbox controller thing is affected by running games through Proton if at all? If it matters let me know, and I'll see if I can procure a controller for myself.