You can now use a Nintendo Switch Pro Controller with your Android phone
Thursday, November 7, 2019 at 6:20AM 
One solution to make it easier to play mobile games on smartphones are external controllers. Android continues to add support for external controllers to make it easier to game on your mobile device. The latest one to get support is the Nintendo Switch Pro Controller. Technically, you could connect the Pro Controller before because it's a Bluetooth device. But functionality might be hampered. This time, the controllers are correctly mapped—allowing you to game freely.
To pair your Pro Controller with an Android phone, simply hold the pair button on the back of the controller and then head to the Bluetooth settings on your handset. Right now, some of the games you can use the controller with include Grand Theft Auto: San Andreas, Minecraft, and Modern Combat 5: eSports FPS.
Source: Android Police