How to Install Retroarch & more on The Xbox Series S and Series X.
Do this at your own risk. Dev mode is an official Microsoft product but the Programs you install are not.
You can also download another multi game emulator Retrix & standalone PSP, NES and N64 emulators from XboxOne HQ link below.
Also should work with Xbox one
If Dev mode gets stuck installing on four bars
How to register for a Dev account
Xbox one hq website download links
Xbox Developers website