In theory, anybody you follow you should see their new threads in Threads on the Subscribed view, and their new microblog posts in the Subscribed/Microblogs view. I am not convinced it actually works for Threads - and it may not work for microblogs either.

Certainly following Mastodon users shows their posts under Subs/Microblogs.

Following Lemmy users should show their posts in the Threads view (as above, not sure if this works).

Boosts should show up as a new post "boosted by" in either Threads or Microblogs depending on what it originally was - but this appears to be unimplemented.