Meta announced that users on Threads will be able to see fediverse replies on other posts besides their own. In addition, posts that originated through the Threads API, like those created via third-party apps and scheduling services, will now be syndicated to the fediverse.
Yep, pyfedi supports Mastodon integration just like mbin.
Not quite as good as Mbin. For example you can’t follow someone on mastodon from PieFed. They can follow you, though.