Well, I just connected an Xbox Controller via OTG USB adaptor to my Android Phone. Not only does it have enough power to support a Gamepad, but it also charges the batteries of said Gamepad.
And because I thought it funny I connected an USB hub via OTG with a CH Combatstick, CH Throttle and pedals and guess what... https://gamepad-tester.com/ recognizes all of them on my phone.
So you might actually be able to connect rather professional hardware to your Android phone.
BTW: Mouse and keyboard will also be recognized by your phone. If it works in Aerofly is another question though.