If you're in a makepkg distro, TKG, author of official Lutris wine builds and other gaming-optimized packages, just released an addon for his wine-tkg that builds a custom proton build.

It benefits from the constant fixes and features wine-tkg has, so you will be able to finally have an updated proton without depending on Valve or rebased forks.

Check it out at https://github.com/Tk-Glitch/PKGBUILDS/tree/master/proton-tkg and remember to report issues and also drop a buck at his Patreon if you find it useful. His support is top-notch.