I tried connecting my Elite controller to my laptop for retroarch and the Xbox button turned a greenish blue. I didn't even know it could do that : r/xbox
RetroArch
RetroArch PS4 controller setup configuration for PS4 LINUX - YouTube
Lakka documentation - Input settings
RetoArch - use of Xbox Guide button messes with Launchbox pause screen closout - Emulation - LaunchBox Community Forums