For what it is worth, I looked to see if anyone had done Nostr over Gossipsub and I came across a project called Gossip. Looks like they are trying to use the Nostr protocol in a psuedo-gossipsub way. That coupled with the proposed Nostr NIP 72 which would allow Lemmy-like communities could make this the solution you were looking for. Obviously these are in their infancy, but it may be an idea to follow.
Reddit is an example of a Group system where posts are associated with a group. This is the model Lemmy uses.
Twitter is an example of a Person system where posts are associated with a person. This is the model Mastodon uses.
Some services can do both; like Kbin with their microblogs and magazines.
Sounds like the Wordpress implementation uses the Person system that Lemmy does not support at the moment, but probably works on Mastodon and Kbin (idk for sure).