How to display GUI in PAM module?

I am trying to add a GTK window in PAM module. It works from my test pam app but doesn't work during desktop login or unlock. I see another unanswered question here - https://stackoverflow.com/questions/59011871/gtk-pam-module-not-showing-on-login Wondering whether this is possible? If not then what is the approach to integrate / customize the login UI (gnome-screensaver, gdm-password) and let my PAM do the authentication.