Hello everybody,
Just to recap, take a look on the official support for Screen/Devices and Countries available at moment:
SCREEN/DEVICES: (where you can play Stadia games) --> Official Link
NOTE: Playing Stadia on a TV requires the Stadia Controller and Chromecast Ultra.
COUNTRIES: (where you can play without VPN) --> Official Link
NOTE: Stadia App can be downloaded in any Android 6.0+ device from Play store. (thanks @bFudg3 for clarification)