The biggest hurdle with Quantum gamepads on Android isn't the connection—it's that many mobile games (like Genshin Impact or PUBG ) don't natively support generic controllers. For this, you need a "mapping" app that acts as the driver by translating button presses into screen touches.
Some phones (especially Oppo, Vivo, and Realme) require you to manually toggle "OTG Connection" in Settings > Additional Settings .
Install it, calibrate it, and feel the difference. Your thumbs will thank you.