https://www.techradar.com/news/steam-link-app-for-android-and-ios-will-allow-you-to-play-games-on-the-go

Soon you’ll be able to enjoy your entire Steam library of games on your mobile device. No that’s not a typo. Well, sorry, it is a typo - Steam will actually be available on mobile devices plus devices running Android TV and your Apple TV. 

Anything that runs iOS and Android, basically.