Also, Threads has introduced extremely strict rules for servers that want to federate.

Entire Fediverse server applications are incapable of following all these rules, either technologically or by concept.

For example, IIRC, Threads demanded a full public timeline. Hubzilla, (streams) and Forte do have that feature in code. But it’s intentionally turned off server-wide by default, and there’s a very good reason for this and for just about no serious admins of public servers ever turning it on.