Laptop Nvidia : Only HDMI Screen...

[Mjölnir]

% cat /var/log/Xorg.0.log | grep VGA
[   301.567] (WW) VGA arbiter: cannot open kernel arbiter, no multi-card support

This is the point of interest! I tried to add the sddm(1) user to the video group, that did not help. There must be a way to achieve that.

I don't know if there is any kind of alternative multi-(card|driver|GPU) support. Nothing is certain with Xorg.

RTFM xorg.conf(5) says: "The config file may have multiple Device sections. There must be at least one, for the video card being used."