The only feasible approach I see is for the distros that want to use interactivity during package update or installation to abandon the use of PackageKit entirely and provide Discover with a custom backend capable of prompting for interactivity in this way. Discover already has custom backends for SteamOS and Fedora Kinoite, so this isn’t as impossible as it may sound.
However it’s still a lot of work and someone who uses the so-supported distro would need to maintain that code. Ideally someone from the distro itself. And of course it requires someone in the distro to care enough about Discover to build such a thing in the first place, since it wouldn’t be code that’s shareable with GNOME Software. This is why the only two custom backends Discover has are from KDE-only distros whose maintainers don’t care about GNOME.