I was wondering, since I didn't really find anything definite via Google but is dual GPU dual display actually a supported configuration in Debian 11?
So basically for a while I ran this kind of setup: Display 1 connected to CPU's integrated GPU (Core i7-4790K, Intel HD Graphics 4600). Display 2 connected to Nvidia RTX3070Ti. The two displays setup as a single wide display, i.e. windows movable/draggable from one display to the other. I have a triple boot setup, Windows 10 worked fine, Arch Linux with KDE was hit or miss, Debian didn't work, no image on one display and xrandr saw only one display. Which one seemed to depend on which GPU was set as primary in the UEFI setup. No xorg.conf but I fiddled with that too. Each OS used Nvidia's proprietary driver since there isn't much anything else for such a new GPU. My minimal video card support is accelerated 2D and 3D and video decoding so wasn't looking for just any video output. The reason for this setup was that Debian 10 has no drivers for the RTX3070Ti so I just used one display there and since it worked in Arch (at least sometimes) I figured it should just start working in Debian 11 after the upgrade but it didn't.
