TIL that lsregister allows to list all x-callback available on your system, e.g. /System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support/lsregister -dump URLSchemeBinding. #apple
/System/Library/Frameworks/CoreServices.framework/Versions/A/Frameworks/LaunchServices.framework/Versions/A/Support/lsregister -dump URLSchemeBinding
#apple