My suggestion doesn’t really get much more complicated than the title.
Discover’s menu for the KDE store/Plasma addons is better than Get New Stuff by orders of magnitude- the landing page for each actually loads and scrolls through more than just ~24 items, image previews in item previews load faster, preview larger and fullscreen larger (which is nicer for checking color palettes and themes) and is overall better performing by multiple times.
Only problem is, there’s very little to hint that Discover is capable of this, nor that it’s any better than the Get New Stuff window. Additionally, it isn’t able to load thumbnails for items. Which, just sucks because if it could it’d just be better than Get new stuff.
I think it’s reasonable to replace Get New Stuff buttons with a link to their appropriate Discover page, and allow loading for thumbnails in Discover, and deprecate Get New Stuff entirely. It really does not work well at all, at least in any amount of personal experience of mine.