Connection to displaymanager possible?

With x11vnc I was able to connect to my displaymanager X11 session (in my case, it's sddm) with a systemd service started from the following file /etc/systemd/system/x11vnc.service:

[Unit]
Description=x11vnc-Server

[Service]
ExecStart=/bin/bash -c "/usr/bin/x11vnc -auth /var/run/sddm/* -display :0 -forever -loop -noxdamage -passwdfile /etc/x11vnc.pass -rfbport 5900 -shared -localhost -ncache -ncache_cr"

[Install]
WantedBy=multi-user.target

I wonder if a similiar thing is possible with x11spice as well?!? The most delicate part is the -auth /var/run/sddm/* thing for which I see no replacement in x11spice...