For those who don't know, the strategy is called Embrace, Extend, and Extinguish. The phase comes from Microsoft who used this to (try to) crush competing document editors, Java implementations, browsers, and operating systems. Other big tech companies employ similar strategies.
Facebook coming to the Fediverse is the Embrace phase of this process and that makes Mastodon, Lemmy, Kbin, Misskey, and Akkoma the competitors.