I believe so, though I cannot find great examples to prove it. e.g. !memes@reddthat.com exists but is empty. Then again, I saw similar occurrences with my old instance, Discuss.Online, when nobody had yet joined !justpost@lemmy.world. So I joined it, waited a day or two, and then all the posts showed up - this is the way that communities used to have be federated, before Blaze went around to virtually every instance and joined almost literally every community to make it already happen for people:-). Anyway, Blaze seems to not have done that for PieFed yet, so I will do it myself.:-)