FreeBSD Installer: using the installer's offline packages

The rough guide below is for:

After a minimimal installation of FreeBSD

Before first boot:

open a shell in the new system
Alt-F4 to step away from the live system
pkg --rootdir /mnt add /usr/freebsd-packages/offline/FreeBSD-bsdconfig-15.0.a5.20251004102635.pkg
pkg --rootdir /mnt add /usr/freebsd-packages/offline/FreeBSD-csh-15.0.a5.20251004102635.pkg
pkg --rootdir /mnt add /usr/freebsd-packages/offline/FreeBSD-ee-15.0.a5.20251004102635.pkg
Alt-F1 to step back to the live system
/bin/tcsh
ee /etc/pkg/FreeBSD.conf
add a repository configuration (the four lines below), save the file
pkg update --repository freebsd-installer-nonbase
pkg install --quiet --yes -r freebsd-installer-nonbase kde plasma6-sddm-kcm sddm xorg
similarly, install other packages that may be required for your computer
service dbus enable && service sddm enable
exit
exit
reboot, shutdown, or revisit the live system.

freebsd-installer-nonbase {
  url = "file:///dist/packages/${ABI}"
  enabled = yes
}