Typo: (CoreOS and Fedora Silverblue) are the bleeding edge of immutable distros. Those mentioned are just users.

GNOME OS uses BuildStream and as a result has no concept of packages at all and no relationship to any distro, KDE Linux is based on Arch. There is no relationship between the two. GNOME OS used to be OSTree based but switched to systemd-sysupdate a while ago.