Found some time earlier than expected, so here are the basic differences of my fork:
- It makes each federated category/tag behave much more like a real Lemmy community (Group actor), including its moderators, featured posts, follower rules, and shared inbox.
- A Discourse topic can be sent as a Lemmy-compatible Page (with replies as Notes), rather than only the formats upstream offers.
- Votes federate: remote upvotes/downvotes become Discourse likes, and the federated score is shown on posts.
- Moderation federates in both directions: removals, bans, locks, moderator changes, reports, and featured/pinned posts can be communicated to compatible remote communities.
- Discourse users become proper, followable ActivityPub people. Mentions are also resolved for federation.
- It can follow a remote community—for example on Lemmy or NodeBB—and present it inside Discourse as a local “shadow category.” Local users can then read and participate from Discourse.
- It adds an instance-level actor and optional “authorized fetch,” which can require signed ActivityPub requests when other servers retrieve content.
- Administrators get extra tools: community/federation health view, remote-community management, per-community ban management, URL/content resolution, and bulk republishing/backfill.