The work-around to play Xbox cloud games on Windows 10 PCs no longer works due to a change from Microsoft. The workaround worked with a test version of the streaming app intended for Xbox devkits.
Several users report on reddit that the work-around no longer works. That would be due to an adjustment of the offering id. As far as we know, no new method has yet been found to get Xbox cloud gaming working again via the app on Windows 10 PCs. Streaming games from an Xbox console to a PC, according to users, still works.
Last week it was revealed that it was possible to play Xbox cloud games on a Windows 10 PC. This required an app to be installed that is actually intended for Xbox devkits. The app then asked for an offering id, and by entering XGPUBeta, access to the streaming service could be gained. Presumably Microsoft has modified that code.
Xbox cloud gaming has been available on Android devices since last year. To use it, users must have an Xbox Game Pass Ultimate membership. Microsoft is also working on a Windows 10 app for the service, but it has not yet been announced when it will be officially released. Microsoft also wants to bring the service to iOS and iPadOS, but Apple is blocking that. This may eventually work via a web interface.
Test app for Xbox game streaming on Windows 10