I am surprised to see that this quite Linux centric community missing the obvious. With Stadia support 'cleaned up' from game engines it is a game over for Linux desktop gaming.
Fortunately the Steam Deck[0] is still helping push for Linux game support although their approach is centered a lot more on emulating Windows games. According to their Steam Deck verified[1] program it seems to be working.
Stadia has contributed almost nothing to linux gaming. We never saw any of the stadia games released natively for linux. All effort that is done is by valve, with proton. And proton runs windows games.
I'd argue that linux native is dead, but that doesn't matter much when we can just run windows games.
[0]: https://store.steampowered.com/steamdeck [1]: https://www.steamdeck.com/en/verified