update-manager's config format has a way to configure 'KeyDependencies' of a meta package (i.e. neon-desktop). If the metapackage is not installed a system may still be identified as belonging to the metapackage if some of the key dependencies are present.

This can (I think) be put into the neon.cfg. For reliablity reasons it may be better to put it in the release-upgrader? In fact, neon.cfg may better be put into release-upgrader? (add a task for this maybe)

list proposal:

plasma-desktop, plasma-workspace, breeze, neon-settings