…by 10 users between 2014 and 2022…wow 
including PC World or Microsoft Store 
Not sure why you don’t just use the flatpak version (as your user) and then use Flatseal to tighten/loosen permissions.
How does it solve the problem of automatic updates?
Tumbleweed also has no automatic update/upgrade.
The equivalent command for zypper dup is flatpak update (only for the flatpak apps…)
As NAPS2 is available on flathub, flathub serves as “repository”.
Now read this topic and ask yourself why zypper dup cannot be used.
I did. And i know the difference between a rpm provided by a openSUSE repo, and a flatpak available on flathub. To update the rpm you need to use zypper dup. To update the flatpak you need to use flatpak update.
So what is your point regarding “automatic updates”?
There is no rpm repository for NAPS2, but flathub for the flatpak version of NAPS2 (according their description on github).
The NAPS2 devs did a big mistake whilst “setting up” the flatpak. On their downloadpage they point to the documentation how to setup flathub. But they fail to provide their project on flathub itself but only provide single standing flatpaks…so arvidjaar had one point. The update via flatpak update won’t work as the NAPS2 devs failed badly by not setting up their project properly on flathub.