Ubuntu-desktop repeatedly not working on boot
Since you have purged all of your nvidia* packages, it's likely that you are now using the nouveau driver, which you can check by running lsmod | grep -Ei nvidia\|nouveau.
I had reliability issues with the 460 and 465 versions of the nvidia driver, which I fixed by downgrading to version 450. You can see a full list of available drivers with apt list nvidia-driver-*