It seems that GDM in Wayland session is not able to run GUI window directly after login. Example listed below is not able to display window and session get stuck. $ cat /etc/gdm/PostLogin/Default /usr/bin/zenity --info I already noticed similiar issue on internet. Not sure if it's specifically Gentoo issue, but in case you think it's GNOME fault, please keep open and I'll link their bugreport. Thank you
Nothing we can do downstream. GDM doesn't have a GUI itself (anymore), it uses gnome-shell for that. There's discussion in upstream bug about this (now at https://gitlab.gnome.org/GNOME/gdm/issues/340 ) Seems like you need some sort of input before login. There's now some sort of pam extension mechanism shoehorned into gdm since v3.28 that allows pam to ask questons from gdm, albeit probably still just a choice list. Maybe this can be utilized with some upstream work to do what you need - https://bugzilla.gnome.org/show_bug.cgi?id=788851 added that stuff and has more details. Closing this bug here, as nothing we can do here, given the technical nature of the related stuff now.