NodeBB has a very simple allow/deny list capability at present. You paste in a bunch of newline-separated domains, and we block (or optionally, only allow) them all.
Currently I am grappling with the specifics behind how to federate out the deletion of a topic in a category (or in ForumWG terms, the deletion of a context from an audience.)
nutomic@lemmy.ml reported a federation issue with a NodeBB instance and we debugged it. It turns out Lemmy is unable to handle actors who have image or icon set to null.