Here’s a table of which Fediverse servers are federating or de-federating Threads.
Of the top 10 most active servers it lists, eight of them are federating, one is offering limited federation (
infosec.exchange), and one is de-federating Threads (
mas.to).
Of course, there’s some notable large servers missing from this list. For example, is
misskey.io federating with Threads?
https://fedipact.veganism.social/@fediversenews