If I understand correctly, users of other fediverse things like Mastodon can follow lemmy communities (and users?) but the reverse is not currently possible. Would it not make sense for lemmy users to be able to subscribe to a hashtag or user on a mastodon instance?
It takes time because, even though the ActivityPub standard is just one standard, every platform adds their own spin on it and the data doesn’t match up exactly. It’s unfortunate but the flexibility of AP allows us to have youtube and instagram equivalents on the fedi.