Mastodon can reply to federated Threads posts.

SOURCES

Mastodon17

Bluesky3

Jul 11
did:plc:uu7vkrzmovjmhl6kwz5snuzf
Posted on Threads, checked on Mastodon and replied via Mastodon, and got the notification in Threads. Just need to be able to reply and then I can remove one social media platform from the phone and still get interactions ✌️
Jun 27
@starrwulfe@starrwulfe.xyz
Could this be the #fediverse explainer we were looking for? Click to load "“Welcome to the fediverse: Your guide to Mastodon, Threads, Bluesky and more” — TechCrunch"techcrunch.com may use cookies #read #micro #note
Jun 27
@superj104@www.threads.net
Mission Accomplished. Used a Mastodon account to respond to my post on here. Screenshot of what it's looks like on Fediverse Threads.
Jun 26
@rogarcia_sanz@www.threads.net
Replying to my Threads federated post on mastodon.
Jun 26
@crozilla@sfba.social
Welcome to the fediverse: Your guide to Mastodon, Threads, Bluesky and more