Ha good eyes! :) I have basic receive-only working with Lemmy using a virtual file system interface I wrote (https://pkg.go.dev/olowe.co/lemmy). Just realised we actually spoke about this a while ago haha (https://lemmy.sdf.org/post/1035382 )

But synchronising to disk is super inefficient: too many API calls. Should subscribe using ActivityPub proper and store updates received as RFC 5322 messages.

From there we could serve the messages via NNTP. Then, finally, we could use nntpfs(4)