https://www.polygon.com/2018/5/9/17337612/steam-link-mobile-android

Steam Link, the application that serves games played via Steam to a connected television, is coming to mobile devices, Valve announced today.

A Steam Link app is due to launch May 21 for Android and iOS devices, Valve said. If these devices are connected to a 5 Ghz network (or wired by ethernet), users may play their full library of Steam games. The Steam Link app for mobile devices will support the Steam Controller, MFi controllers and other peripherals.