Great article! My two points to add are that Threads has 200 million monthly active users, while Flipboard has between 100 million and 145 million monthly active users.

The rest of the Fediverse boasts between 1 million & 2 million monthly active users (around 20 million accounts total, but most are not active or are hard to track activity).

That said, I believe the Fediverse will eventually surpass a billion monthly active users before the end of the decade, especially as more blog platforms join.