You're delusional.
The fediverse stuff is just a bullet point on a sales sheet, Facebook doesn't give a shit about federating with Lemmy or Mastodon or whatever.
The reason they don't give a shit is they already have a user base that is multiple times larger than Lemmy and Mastodon combined. Also normal people don't even know what those things are. My mom doesn't know what Mastodon is, she does know what Twitter and threads is.