Recently, I was thinking about adding a new feature to microblog.pub: the possibility to pull/subscribe to a RSS/JSON feed and create Article activities when a new post is published.
On the "public" website, it would show up as a link to the original post (like Mastodon is doing), but the AP object would contain the full post.
This way, your blog (#IndieWeb powered of course) would be able to fetch the replies/likes/shares collection of the Article and display it.
So, you are invisaging this feature being used by the owner of the blog and the microblog.
I think there is also a bot potential, to aggregate info from third party sources. Perhaps, that isn't the intention.