Hello Gwen Sutton,
Good news, there is a single toggle for exactly that — the controller-button trigger has its own switch and it's separate from uninstalling Game Bar (which, as you found out, just makes Windows nag).
Open Settings > Gaming > Xbox Game Bar. Turn off "Open Xbox Game Bar using this button on a controller."
That alone stops the Xbox button on your fightstick from launching it. You can leave Game Bar installed so Windows stops complaining.
If you also want Win+G to do nothing (so it can never pop up by any means), the cleanest way is the registry — open Registry Editor and set:
HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\GameDVR>AppCaptureEnabled= 0HKEY_CURRENT_USER\System\GameConfigStore>GameDVR_Enabled= 0
Sign out and back in (or reboot) and Game Bar will no longer launch from anywhere, while the app itself stays installed so Windows doesn't keep looking for it.
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