As I like to have a lean Plasma 6 Wayland environment, I started to trim down my Neon installation by setting the “–no-recommends” as default and by removing as much as possible kf 5.116, qt 5.15 and xorg packages (there are lot of them in Neon). To my surprise I also got rid of plasma-discover package (what is OK, as I manage packages at command line anyway). Do I understand correctly, that plasma-discover has not yet migrated to qt6 & kf6 & plasma6?
It is qt6, kf6 on arch.
Could be related to Neon using Ubuntu LTS. I’m glad KDE has decided at last to move away from that non-working concept. You can find the various versions of plasma-discover here (though not always 100% accurate, as OMLx ROME is using both plasma6-discover package versions - Repology):
Available package in current KDE Neon User is plasma-discover-6.2.5-0zneon+24.04+noble+release+build18.amd64.
However, when I try to install it, it requires a lot of kf5 & qt5 packages:
$ sudo pkcon install plasma-discover
Resolving [=========================]
Testing changes [=========================]
Finished [ ] (0%)
The following packages have to be installed:
apt-config-icons-hidpi-1.0.4-1+24.04+noble+release+build1.all APT configuration snippet to enable HiDPI icon downloads
apt-config-icons-large-1.0.4-1+24.04+noble+release+build1.all APT configuration snippet to enable large icon downloads
apt-config-icons-large-hidpi-1.0.4-1+24.04+noble+release+build1.all APT configuration snippet to enable large HiDPI icon downloads
debconf-kde-data-1.1.0-1build3.all Debconf KDE data files
debconf-kde-helper-1.1.0-1build3.amd64 Debconf KDE GUI frontend tool
kde-config-updates-6.2.5-0zneon+24.04+noble+release+build18.all Dummy transitional
libdebconf-kde1-1.1.0-1build3.amd64 Debconf KDE GUI library
libkf5archive5-5.116.0-1zneon+24.04+noble+release+build3.amd64 Qt 5 addon providing access to numerous types of archives
libkf5auth-data-5.116.0-1xzneon+24.04+noble+release+build2.all Abstraction to system policy and authentication features
libkf5authcore5-5.116.0-1xzneon+24.04+noble+release+build2.amd64 Abstraction to system policy and authentication features
libkf5codecs-data-5.116.0-1zneon+24.04+noble+release+build3.all collection of methods to manipulate strings
libkf5codecs5-5.116.0-1zneon+24.04+noble+release+build3.amd64 collection of methods to manipulate strings
libkf5completion-data-5.116.0-1zneon+24.04+noble+release+build3.all Widgets with advanced auto-completion features.
libkf5completion5-5.116.0-1zneon+24.04+noble+release+build3.amd64 Widgets with advanced auto-completion features.
libkf5config-data-5.116.0-1zneon+24.04+noble+release+build3.all configuration settings framework for Qt
libkf5configcore5-5.116.0-1zneon+24.04+noble+release+build3.amd64 configuration settings framework for Qt
libkf5configgui5-5.116.0-1zneon+24.04+noble+release+build3.amd64 configuration settings framework for Qt
libkf5configwidgets-data-5.116.0-1zneon+24.04+noble+release+build3.all Extra widgets for easier configuration support.
libkf5configwidgets5-5.116.0-1zneon+24.04+noble+release+build3.amd64 Extra widgets for easier configuration support.
libkf5coreaddons-data-5.116.0-1zneon+24.04+noble+release+build4.all KDE Frameworks 5 addons to QtCore - data files
libkf5coreaddons5-5.116.0-1zneon+24.04+noble+release+build4.amd64 KDE Frameworks 5 addons to QtCore
libkf5guiaddons-data-5.116.0-1zneon+24.04+noble+release+build3.all additional addons for QtGui
libkf5guiaddons5-5.116.0-1zneon+24.04+noble+release+build3.amd64 additional addons for QtGui
libkf5i18n-data-5.116.0-1zneon+24.04+noble+release+build3.all Advanced internationalization framework.
libkf5i18n5-5.116.0-1zneon+24.04+noble+release+build3.amd64 Advanced internationalization framework.
libkf5iconthemes-data-5.116.0-1zneon+24.04+noble+release+build3.all Support for icon themes.
libkf5iconthemes5-5.116.0-1zneon+24.04+noble+release+build3.amd64 Support for icon themes.
libkf5sonnet5-data-5.116.0-1zneon+24.04+noble+release+build2.all spell checking library for Qt, data files
libkf5sonnetcore5-5.116.0-1zneon+24.04+noble+release+build2.amd64 spell checking library for Qt, core lib
libkf5sonnetui5-5.116.0-1zneon+24.04+noble+release+build2.amd64 spell checking library for Qt, ui lib
libkf5textwidgets-data-5.116.0-1zneon+24.04+noble+release+build3.all Advanced text editing widgets.
libkf5textwidgets5-5.116.0-1zneon+24.04+noble+release+build3.amd64 Advanced text editing widgets.
libkf5widgetsaddons-data-5.116.0-1zneon+24.04+noble+release+build3.all add-on widgets and classes for the Qt Widgets module
libkf5widgetsaddons5-5.116.0-1zneon+24.04+noble+release+build3.amd64 add-on widgets and classes for the Qt Widgets module
libpolkit-qt5-1-1-0.200.0-2zneon+24.04+noble+release+build4.amd64 PolicyKit-qt5-1 library
libqcoro6core0t64-0.10.0-1.1+24.04+noble+release+build5.amd64 C++20 coroutines for Qt6 - Core
libqt5qml5-5.15.16+p24.04+vrelease+git20241207.0159-0.amd64 Qt 5 QML module
libqt5texttospeech5-5.15.16+p24.04+vrelease+git20241207.0331-0.amd64 Speech library for Qt - libraries
libqt5waylandclient5-5.15.16+p24.04+vrelease+git20241207.0330-0.amd64 QtWayland client library
plasma-discover-6.2.5-0zneon+24.04+noble+release+build18.amd64 Discover software management suite
Proceed with changes? [N/y]
Hi - sometimes things that you see installed along with a desired package are not there because of a direct dependency by that particular software, but because that software depends on a component which itself needs additional packages installed.
Just as an example - looking at the results of apt-cache depends plasma-discover, one of the required packages is debconf-kde-helper. Looking at apt-cache depends debconf-kde-helper, one of its dependencies is libkf5i18n5. One of that package’s dependencies is libqt5qml5 - listed in the output you pasted in 
Basically, Discover itself does not directly use Frameworks 5 / Qt 5 components, but at least the current packaging of Neon’s “fresh KDE + LTS base Ubuntu” setup ends up requiring some of those kf5 components to be installed.
That explained it, thanks!