Installing the dbus package in debian-12-minimal template corrected the following observed behavior:
In sys-firewall, based on a debian-12-minimal-dvm,
$ systemctl status
Failed to connect to bus: No such file or directory
After installing the dbus package in the debian-12-minimal template, this error disappears and services such as qubes-firewall run as expected.
@unman dbus was included in the debian-11-minimal template. Should it also be included in debian-12-minimal, or is there some other fix for this error?