I used a similar setup for a while but the input lag from emulators on android is noticeable, made far worse through a Bluetooth controller connection :( I went back to using my old PsP and had a blast retro gaming!
Thought I’d miss the ease of use, everyone always has their phone with them after all. But the controller attachment is far bulkier and less pocketable than the entire PsP!
Now I use the original Switch to scratch that retro itch