Black Screen when Nvidia connected, Software and Updates don't see card anymore, GDC used, GT 1030 fan running

Graphics / Linux Linux
4

The post you linked is irrelevant. To get what you want, basically you just need to enable the egpu for graphcs use and enable prime.
If you have any /etc/X11/xorg.conf created, delete it. Then create /etc/X11/xorg.conf.d/10-nvidia-egpu.conf only containing

Section "OutputClass"
    Identifier "nvidia-egpu"
    MatchDriver "nvidia-drm"
    Driver "nvidia"
    Option "AllowExternalGpus" "True"
EndSection

After reboot, the gpu should be in offload, aka on-demand mode
https://download.nvidia.com/XFree86/Linux-x86_64/495.44/README/primerenderoffload.html
If you want the nvidia gpu render everything, change it to

Section "OutputClass"
    Identifier "nvidia-egpu"
    MatchDriver "nvidia-drm"
    Driver "nvidia"
    Option "AllowExternalGpus" "True"
    Option     "PrimaryGpu" "yes"
EndSection

If anything fails

,