I only mentioned the separate X session part because that has been suggested as a "workaround" for over half a decade; hence why I even have that setup on my old install. I was simply anticipating someone posting a response claiming that it would work with such a configuration as I know the inevitable answer (I revisit trying Linux on this computer maybe once a year).
> Since the vast, vast majority of people nowadays do not run multiple X screens, there isn't a lot of interest on the part of desktop environment coders to get them working (also because likely they don't have that hardware themselves and so can't try it either)
Yup, I get that it's uncommon. It's just sad that what used to work years ago has regressed and simply does not work at all anymore. I also considered doing the .xinitrc thing you suggested, but stopped myself from wasting more time as it would just result in a frankenstein DE that wouldn't be very usable (Gnome & KDE are quite far apart in usability philosophy).
(edit: Also remember that to a non-technical user, they would simply try what the GUI suggests. Nvidia defaults to separate X sessions across different cards. Since DEs don't work with that configuration anymore, that would appear no different than a driver issue to the end user.)
> This constant regression in features is what I dislike most about Linux lately. Eternal September in software form.
This is what pushed me from using Linux full time for almost a decade to jumping ship to Apple a year ago. That and people like AsyncAwait who never seem to respond to people like me who post concrete real world problems despite claiming everything negative is FUD.
> as separate X sessions like in my old install (depending on the DE I choose, either no DE is launched on the other monitors, or they do launch but the only way to run programs on the other X sessions is to manually configure the DISPLAY value to those screens and launch the program in a terminal).
the issue is not with the drivers, but with whatever DE you want to use. Since the vast, vast majority of people nowadays do not run multiple X screens, there isn't a lot of interest on the part of desktop environment coders to get them working (also because likely they don't have that hardware themselves and so can't try it either)
I personally also run two separate nvidia cards with two separate X screens on them, I run i3 but have had to patch several things to get it to work well enough for myself, it was doable for me to patch i3 due to having spent many years deep into X11/Xt way back, but definitely not something the average user could do and not something useful enough to a large enough number of people to warrant including in it for everybody
A desktop environment coded to expect that it's run once per computer in general won't like being launched twice in parallel (one for each screen), if you want something easy I suggest doing something like running KDE on your primary card and Gnome on the other: you will very likely have to mess with your .xinitrc to launch each separately on :0.0 and :0.1 but it should be doable