Ahead of its planned rollout in spring of 2021, Project xCloud—the Xbox game streaming app—is up and running on Windows 10. Late last year a method for downloading a Spanish test version of the relevant app circulated on Twitter and Reddit, and though some users reported that audio didn't work for them or that it was broken by Windows updates, others managed to stream Xbox games available with Game Pass Ultimate on PC.
Ars Technica recently tested it out and found that, at least with a wired connection to the internet, it's possible to stream games like Killer Instinct with a tolerable amount of lag. Most of the games only support gamepad controls rather than keyboard-and-mouse at this stage and run at 1080p, but that's better than you'll get running them on your phone.
You'll need to have a subscription to Xbox Game Pass Ultimate to try this yourself, and the test app is updated frequently enough that the download instructions will probably be out of date by the time you read this, so I leave finding them as an exercise for the reader. The YouTube channel Cloud Gaming Xtreme has been keeping on top of it and trying out games like Outriders.
While the games available are mostly cross-platform ones, the backwards-compatible section of Game Pass Ultimate does include some Xbox 360 exclusives. This'll be one way to finally try Fable 2 on PC.