Your new Steam Controller will not work with the Xbox app and PC Game Pass unless you use third-party software on Windows

Game Pass titles from the Xbox PC app can't communicate properly with Valve's new controller via Steam Input, an issue that's ...
Windows Report

Steam Controller Struggles With Xbox Game Pass and PC Apps

Valve’s new $99 Steam Controller is running into compatibility problems outside the Steam app, especially with Xbox PC games and third-party launchers, as Windows Central reports. While the controller ...