I am pretty sure Discover can be used without the PackageKit backend.
It is the main software management frontend of KDE Linux and that does not have traditional packages either.
Making an educated guess about our current setup, I think the process that “knows” this status is DiscoverNotifier and it displays that status as an icon (in various states) in the system tray area.
Assuming this is true, we could additionally expose this status as one or more D-Bus properties.
This could then be used for two things:
- other places in Plasma could show the status, e.g. any of the shutdown/logout/sleep applets, the application menu button, etc.
- a distribution which does not ship Discover (for whatever reason) could simply provide a session service with the same D-Bus name/path/interface and their Plasma users would still see the status as if they had DiscoverNotifier running