When the nvidia drivers are reinstalled either through the upgrade-packages action or through the charm, the worker will need to be rebooted in order to use the GPU. We should surface this need to the users by setting a message (and possibly blocked status) in juju status.
This requirement also highlights the issue found in LP#1982894 where changing the sources or the packages will always cause a reinstall. There should be a check added to see if there is a change in what should be installed prior to uninstalling/reinstalling.
Additionally, we probably shouldn't be autoremoving stuff that isn't relevant to what we are trying to do. For example, I have seen a kernel get autoremoved through this functionality. We should attempt to limit the autoremoval to just what our needs are.
Example:
https://pastebin.ubuntu.com/p/NwcrQGkk4h/
Provides a warning on upgrade that a reboot may be needed:
https:/