Comment # 1 on bug 1041120 from Dominique Leuenberger

GNOME Software only shows applications that ship appropriate metadata - that is
definitively far from all of them.

The current trend of apps showing up can be seen at
https://gs-stats.opensuse.org

This is working as intended (well, intention would be more apps) - but there is
not 'one' bug in the software center, but rather 'a lot of bugs in the packages
not showing up' (granted, some better not show)

I'll tag it as a FEATURE - but this needs somebody persistent to be after the
packagers to get this done. Maybe that could actually be something you could be
doing? There are some others already adding the relevant pieces where possible