The only other alternative suggestion I have is to make sure there is rdfa or microdata markup on all pages.<p>Rather than have an explicit protocol for social media apps, the idea is that anyone can do whatever they want: it's all just stuff on a page. Then we interoperate by writing scrapers that can "see" the standard posts, pictures, calendar events, marketplace postings, &c.<p>ActivityPub is probably a better basis to work from, all in all. There are some advantages though to making social media pages more semantically expressive, to decomposing the page from a big monolithic thing into a thing that has other things on it.
A quick reminder that the Fediverse is not a new concept at all - it recently celebrated its 13th birthday:<p><a href="https://news.ycombinator.com/item?id=27201389" rel="nofollow">https://news.ycombinator.com/item?id=27201389</a>