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
Literally my first exposure to Threads as an active web service tells me that even if it weren't a blatant attempt at Embrace-Extend-Extinguish, you do not want to be federated with it. All your "favourites" from Twitter are there.