Sysv at least gave you a peak under the covers when you used it, and while it may have given people headaches and lacked some functionality, was IMHO simple to understand. Of course the entire spaghetti of scripts was hard to understand in terms of making sense of all the dependencies, but it felt a lot less like magic than systemd does.
I believe it's `systemctl list-unit-files` to see all the config that's executed, included by the distro, and then if you want to see the whole hierarchy `systemd-analyze dot | dot -Tpng -o stuff.png`
To me, seems much easier to understand what's actually going on, and one of the benefits of config as data rather than config as scripts.
The only other page that covers it is how to compile it and it install it (make configure, make, make install essentially- with a bunch of flags).
It kind of touches upon a few commands that will let you know what its doing and how to get it started, but from this page you don't learn much about how it works.
In fact, one of my takeaways from LFS was that I already kind of knew how a linux system starts... and what I really wanted to learn was how the devices are discovered and configured upon startup to be used, and that is pretty much all done in the black box that is SystemD.