Before you ask “why aren’t you running Starfield with Steam’s Proton Experimental or Proton-GE” let’s say I went out sailing yesterday and met a fellow legitimate sailor who was giving many people a great discount on the game.
In spite of this, before you try working all this out, I do want to make sure that you are aware: you can add Starfield from another vendor as a “Non-Steam Game”, still use Proton, and likely avoid all of it.