From what I can tell at the moment there is only communities (but tptb have commented in ways it looks like that might change at some point?). It's a lot more like tumblr than LJ/DW in the way it seems harder to make friends and keep up with people as opposed to just come across comms and people there with similar interests.

I honestly haven't found a lot of interesting comms. I joined a bunch of fandom ones but there's not a lot happening on any of them. The main imzy commm has a lot that might be helpful https://www.imzy.com/imzy. There's a bunch of general fandom type ones https://www.imzy.com/fandom_calendar, https://www.imzy.com/fandom_dealer (the new crack-van like one) and https://www.imzy.com/fandomsoapbox that might have potential, but basically I type random things in the search and see what pops up.