Cool. I'm pretty excited for the new login manager. Maybe now KDE will be able to fit all customization options (wallpaper, lockscreen, login screen) on a single Settings page.

Is there a CLI way to dump/restore those settings?

I'm not certain about CLI, but Plasma 6.6 does allow preferences / settings to be exported & restored / shared.

https://youtu.be/RuxNnfllxco?t=3894 - Neal Gompa on the Fedora 44 Release party stream,