bluesky is more federated than threads, but less federated than mastodon. As I understand it, you can more or less host your own bluesky "instance". Though it is difficult to do and some parts you have to build yourself, it is technically doable. This is not the case on threads, I believe.
I've recently read about that myself. But hosting anything Bluesky-related yourself is horrendously expensive because you need absolute monster servers with terabytes of disc space. Not to mention Bluesky's convoluted architecture.