Yeah it’s a bit of a nightmare. If you want to play the base game without any mods, I think it should work fine just using Proton GE now. But if you want the HD texture pack you have to jump through so many hoops.
I imagine in a few months the process will be streamlined, but this seems to be the only way to get it working at the moment.
I spent hours trying to set up the GUI and couldn’t get it to work. Tried the AUR, Flatpack etc and no luck. In the end I just set up the command line version of open VPN with an Alias.