At its E3 conference today, Bethesda announced Orion, a "collection of technologies" that optimizes game engines for streaming on cloud services like Google Stadia.
So to be clear, Orion isn't Bethesda's own game streaming service. It is something game developers can integrate with their games to "provide players with a fundamentally better streaming experience." The first example of Orion in action is provided by Doom 2016, which is one of Stadia's launch games.
On stage, Bethesda demonstrated Doom streaming to a phone, and claimed there was no "perceptible latency," though that's obviously not a claim we'll just take at face value.
We'll be able to try Doom streaming ourselves, though. No details on the trial were announced, except that you've got to join the Doom Slayers Club tonight for a chance to get in.