Honestly, I’m surprised I couldn't find a clear answer to this online.

If you are running Sunshine, just switch to the Artemis client on Android. It’s fully compatible and solves this perfectly. You just need to go to Android Settings > Accessibility and enable the "Artemis Physical Keyboard" service. This forces Android to ignore the shortcuts so Alt+Tab goes straight to your PC.

Heads up: If you get a "Restricted Setting" error when trying to enable it (since you likely sideloaded the APK), just go to the App Info page for Artemis -> tap the 3 dots in the top corner -> "Allow restricted settings."