This was a quick and dirty design to extend the phone holder portion of my controller mount to use with the Microsoft Surface Duo.

The controller mount that I have is no longer for sale, but this looks like a rebranded version of the one I have:
https://www.amazon.com/Anfiner-Controller-Steelseries-SteelSeries-Controllers/dp/B07CLJF3V7/ref=sr_1_4?dchild=1&keywords=xbox+controller+phone+mount&qid=1609426910&sr=8-4