Comment # 17 on bug 1128853 from Lukas Ocilka

In general it's possible to run YaST inside transactional-update, e.g.

  transactional-update pkg install yast2-dns-server
  transactional-update --continue run yast dns-server
  reboot

but YaST is a complex tool that handles several things at once (checking and
adjusting services, installing packages, writing files, running commands) and
many things just do not work in chroot (transactional-update).

YaST nowadays rather calls `systemctl` than listing files (services) and
parsing them by itself. The same applies to system settings: if not really
needed, YaST calls localectl instead of writing files directly. That's the way
how SUSE wanted systemd to be supported. Well, even better, by calling DBus.
Systemd/DBus do not work inside chroot.