@michaelc @mmasnick From the article : “Soon, our app will be compatible with certain other apps like Mastodon,” Instagram’s slide says. “Users on these other apps will be able to search for, follow and interact with your profile and content if you’re public, or if you’re private and approve them as followers.”
So it appears it is both ways.
(either that or only fediverse users can see instagram content, wich would not be useful to meta)