I'm using GpdControl, and I try to assign L4 and R4 to SysRq and Pause as per Aru's video, but the configuration disappears as soon as I enter it and the buttons don't do anything when I test it in the Steam settings.
Solution
absolute worst case scenario, you can install + use pyWinControls directly. the GPDControl plugin is basically a UI Wrapper for it https://github.com/pelrun/pyWinControls/