Launching Steam games mutes ALL audio from all apps/windows/etc.

more like my games and apps but can launch games without having to open steam or epic etc and find the game and launch it instead just press windows + G and then launch a game straight from there

You can install xbox games for Windows 10 titles in the xbox app and you can launch from the same client just like steam

This allows you to use cloud saves etc

You can always try UWPHook which is a free tool that adds all the windows store and gamepass games into the steam launcher and then you can use launch options in steam to manually adjust the screen size etc, i had to do this for the odd game, not sure it works on all though.

UWP Hook is a simple free little application, when you run it, it adds all the installed gamepass and windows store games into steam, you can launch the games from steam, this may let you use the controller config from steam to allow use of the controller.

I believe the TC is trying to add The Windows App version of FH5 to the Steam launcher as a none steam game. This isn't possible.

Unfortunately due to the DRM the Xbox App installed games still use, it's not possible to add these games to your Steam launcher as none steam games.

GoG Galaxy does allow you to add games from any PC launcher, including the games from the Windows Xbox App.

If you want to stream the Xbox App version of FH5 via steam, you should still be able to by this by launching Steam in Big Picture mode and then minimising to the desktop.

On the other hand if your question was about transferring the game from Windows to Steam then that's not possible. If you want to own FH5 on Steam, you'll need to buy the Steam version.