

Strange, I didn’t have any issue, but it is true that I have an old gtx.
First of all, connect both displays to the same board, or you may have strange issues with the vrr and accurate color display.
Second use this Guidefor the drivers, once the repos are added you can use the graphical package manager for selecting the Nvidia drivers.
During the installation, Nvidia drivers needs to be compiled for your specific kernel version, so it always takes a bit of time.
And nothing else to do, Nvidia are always a pain in the ass, specially with his tendency of making the drivers incompatible between minor kernel updates, so if you didn’t select it during install, activate the automatic snapshot for the zfs before and after updates, in case there is something not properly updated you can rollback, continuous working for a few days until all the changes are propagated to all packages and update again.

Did you run the new recommends?
Usually this is enough for regular drivers