A solution to my problem of getting a second monitor to work via an HDMI cable does not appear to be forthcoming. However, I have now found out that...
What version of Ubuntu is this? That makes a big difference. PopOS is 'Edge', so is running a lot later kernel 6.8.x) than Ubuntu 22.04.4 w/ the HWE...
Also the setting in the GDM conf file... <--- Becaseu that has a setting there locking root out also. Then after all that, you would have to generate...