The PlayJam GameStick had native support for using mobile phones as game controllers via its Companion app. Youtube still has a the official demo video showing it' usage.
When starting the app, it would show the GameStick and you could connect to it. Then the GameStick would deliver a branded controller skin to the app, which then displayed a custom controller interface for the game (or the standard one if the game had no own).
While looking through the files of a GameStick backup, I found some of the cached files in the /data/com.playjam.ca.service/files/ directory: .bundle and .meta files. The .bundle files are just Zip archives that contain an XML configuration file, background, button and stick images.
I took the time and built some little scripts to convert the XML configuration file via XSLT into a SVG image, and a script to embed the bitmap image files into the svg file. They can be found in the companion-app repository on Codeberg.
Game controller images
