I personally am quite against it. I joined Lemmy to stay away from the toxicity on Meta's platforms. I don't want any corporate bodies on the fediverse either and possibly doing to the fediverse what Google did to XMPP
Seems clear to me that Facebook should have no other interest in this other than ultimately making money. Thus it is antithetical to Lemmy and the fediverse in general, and should be treated as such.