I have both KDE neon and EndeavourOS with Plasma. Discover is present on both systems but I notice that EOS doesn’t have a Software Update section in System Settings.
In KDE neon, the Software Update section provides this:
Is the absence of this section common to Arch-based distros or a choice made by EOS developers?
I think that discover and graphical updates are not part of arch. It’s not eos specific. It’s rather that the other distros have implemented it. Same for gnome software, doesn’t work for software install.