SUMMARY Discover has no way to install new library packages or the -dev packages needed for developers. This is a regression from muon which discover seems to have replaced. Developers need more than just the application and plugin packages that non-devs use. I greatly prefer not being forced to use the error prone commandline for this and try to guess what a package is called in my distro. SOFTWARE/OS VERSIONS Linux/KDE Plasma: 5.20.4 (available in About System) KDE Plasma Version: 5.19.5 KDE Frameworks Version: 5.74.0 Qt Version: 5.14.2 ADDITIONAL INFORMATION
this is intentional; Discover is meant to display user-facing software. It is not intended to be a full graphical package manager. Personally I agree with you and would like to see this integrated, but Discover's maintainer disagrees. Until his opinion changes, it'll have to stay this way, sorry. :)
*** This bug has been marked as a duplicate of bug 333438 ***