@w4tsn well, in fact what it does is subscribe to org.gnome.SettingsDaemon.Smartcard and follows the removal of any token identified by the system as used for login. I don't know yet how it does that... I have pam_yubico in gdm and it seems to detect it like that, so any method that results in dbus being used in a way that GNOME detects it will work. In the code there is zero references to brands.