I have a prototype https://kde.carlschwan.eu/distributions very inspired by https://kde.ru/distributions ;)
It contains only major distributions with Plasma as default/or as option during the installation. The first two distribution are KDE Patrons and
the third is a KDE project.
I think I could add the fedora KDE spin too and a small explanation at the end that a user can install KDE applications and plasma in other distributions.