it's not actually clear to me who mods the communities. I created a couple, but don't see any tools to do any moderation, and looking at the docs, it seems it's the instance mods who would do it, and low-level stuff (reporting, blocking) can be done by any user

I haven't investigated too thoroughly though. I really have no interest in investing that kind of time, which is a problem in growing a new place in and of itself