The PowerCore Play 6K is a power bank specifically designed with smartphone gaming in mind. Not only does it has a controller-grip-style shape, it also packs a fan for active cooling. It is compatible with Android and Apple mobile devices, and is available on Amazon from now.
https://www.notebookcheck.net/Anker-s-new-PowerCore-Play-6K-is-a-mobile-gaming-grip-power-bank-and-phone-cooler-in-one.484945.0.html
Can't imagine this being very competitive to physical controls, it's a battery and a fan in the shape of a grip.