@Edent I just released, by looking at my other bookmarked post on this topic (which you wrote on socialhub!), that you already knew about it.

→ https://socialhub.activitypub.rocks/t/list-of-followers-isnt-available-to-mastodon/4717/7

I hadn't made the link earlier. Sorry.

@Edent @colours Doesn't this describe what you need to do? → https://docs.joinmastodon.org/spec/activitypub/#follower-synchronization-mechanism (I haven't tried this yet, just bookmarked it for further research/tries).