Add protonplus.

nodes/hosts/common/programs/steam.nix

@@ -16,6 +16,7 @@
       extraCompatPackages = [
         pkgs.proton-ge-bin
         pkgs.steam-play-none
+        pkgs.protonplus
       ];
       package = pkgs.steam.override { # Fix Overwatch and other games showing wrong timezone in-game.
         extraProfile = ''