This Hugo plugin, is the only one I’ve seen https://git.jlel.se/jlelse/hugo-activitystreams

Include a Replies Collection via Page json, so that Mastodon & other #ActivityPub software can know about all the replies each Lemmy post has

Replies seem to work normally. I meant more like top level posts. Ex: https://social.coop/@django/107294367175203267

Great work!

Question: can only local users post to a group?

(Self hosted) Wordpress is a classic choice. There is even an ActivityPub plugin.