Don't forget Valve though. They don't have as much power as Google, but they have done way more. The Steam Deck (as long as it lives) will help.
Yes[1]. One clue (among hundreds of others) that Stadia was already dead months ago was when the ports dried up, indicating that the project had lost internal funding.
[1] https://gamerant.com/google-spent-millions-stadia-ports/
Aside from marketing efforts, Google seems to have also supported developers with technology efforts, as indicated with the GDC presentation below:
https://schedule2019.gdconf.com/session/first-light-bringing...
[0]: https://store.steampowered.com/steamdeck [1]: https://www.steamdeck.com/en/verified
I'd argue that linux native is dead, but that doesn't matter much when we can just run windows games.