Example projects can be uploaded and downloaded using the KDE "Hot stuff" infrastructure. This infrastructure is already used for themes in LabPlot (GSoC 2016 project).
https://techbase.kde.org/Development/Tutorials/Collaboration/HotNewStuff
The new sections on store.kde.org needs to be requirested similar to how it was done for Cantor in https://phabricator.kde.org/T9980.