The Forthcoming Xbox App Update is Just a Taste of What's Possible
Xbox's streaming feature will work outside of the home, like the PlayStation version, allowing Xbox owners to access and play their games from their Xbox when not at home. The updated Xbox app is being tested by TestFlight members at the current time and will likely see a public launch soon.
That is the point that is really important to understand about this update: this is not the previously-titled "xCloud" streaming service Microsoft wanted to release on iOS. This is effectively a VNC app just like PS4 Remote Play or Screens.
This is of course nice for Xbox One owners, but it is emphatically not the feature Microsoft wanted to ship earlier this month. This new version will let you connect to your personal Xbox One and stream your local games to your phone. While this is certainly a nice to have, it's basically a Plex server of your own movies while Microsoft has Netflix which it still can't release.
If you get value out of this new feature, then enjoy! However, it's worth remembering this just a taste of what is possible, not the best gaming experience Microsoft can offer. Until then, here's me playing Forza Horizon 4 on my Pixel 4 and enjoying it quite a bit.