I wonder if you could use/abuse Mastodon polls (FEP-9967) to distribute posts that provide near-real-time status updates (I'm thinking about severe weather alerts but I'm sure there are other use cases)?
Create a poll with an expiry far in the future and a token set of options (ideally just one—"Do you opt in?"—but poll implementations seem to require at least two).
Nothing seems to prevent the content of a poll from changing—and this is the key insight. The FEP says, "The type of a poll (single choice / multiple choices) and its options might be changed at any time. In that case the author of the poll MUST reset the vote counts." So broadcast updates via the content.
It would be a lightweight way to follow a single item without following the actor, built on top of implementations that already exist.