At the moment I’m slowly experimenting with refactoring kpmcore (not requiring libparted) but it is not part of the current release. The new backend that might appear in later releases can now delete and create partitions but cannot do other stuff (creating partition table, resizing/moving partitions, etc). Hopefully, this will make running KDE Partition Manager and possibly Calamares rootlessly easier. Maybe a GSoC project for next year to finish rootless support if anybody is interested.