Please watch Late Stage Tech's video for full instructions. PC and Android app are both required and must be running for wireless controller input to work.
This video is a demonstration of one workaround solution to get Stadia controllers working wirelessly (over WiFi) on Windows. There's still some issues, mainly with the triggers not working. Hopefully this can be fixed in an update, or hopefully Google releases a software patch or open sources the firmware on the controller so the community can create a better solution.
Note: I don't think is a good solution, especially in it's current condition. I think I'd most likely use another Bluetooth controller I have if I was playing on PC, or just plug in the controller. But I figured I'd share what I found that may work for some people for now.
Games featured in this video: Portal and Hollow Knight
