Look at the new virtual-gamepad in the Steam Link App BETA : r/SteamController
Simple Bluetooth Android Remote Gamepad for 3D VR Glasses Virtual Reality Headset, Easy Control the Android and iOS Smartp… | Vr box, Bluetooth device, Game console
Google Stadia on TVs will let you use your phone as the gamepad | Engadget
Can I use touch to play games when using GeForce NOW on iOS (iPhone) and iPadOS (iPad)? | NVIDIA