This gist has been moved to a repo for better maintainability. Please visit sim2kid/UnityStadiaController for package details and installation.
This package adds definition for the Google Stadia Controller to Unity's Input System allowing for the use of a Stadia Controller natively with Unity.
Thanks! 😁
I've noticed that after turning a Stadia controller into bluetooth mode, it works natively with Unity!
(See https://stadia.google.com/controller)
With your scripts, it will display explicit names for the buttons and sticks though.