Without going into the weeds and all, given they all are in the same project, regardless…
You said “a gui for managing systemd”, so which part? Boot, udev, and journal? All three are required and not optional for systemd the OS infrastructure layer suite (or whatever it’s called these days), so minimally, assume that?
If so, what kind of sane gui could manage those three very disparate things?
Funny enough, I loved that app, and use it for news rather than Google news