Comment # 12 on bug 1182835 from Fabian Vogt

(In reply to Walddys Emmanuel Dorrejo C���spedes from comment #11)
> (In reply to Fabian Vogt from comment #10)
> > pam_systemd will not create sessions if you're already in a session. You can
> > only use systemctl --user from within sessions such as local logins on the
> > tty or X11, or remote logins using ssh.
> > 
> > See also
> > https://github.com/systemd/systemd/issues/7451#issuecomment-346787237.
> 
> thank you for the answer.
> 
> if is possible and can be answered here:
> 
> how can one manage podman rootless if exist this limitation?

You mean running podman as regular user, but outside of a systemd session?
If you want to use rootless podman from a systemd unit, then I suggest to use a
system service with the User= option instead of user services. You might have
to pass "--cgroup-manager=cgroupfs" and set XDG_RUNTIME_DIR yourself.