You're not wrong but you're also not fully right: there has been a second instance that the devs have been using to test out the federation code. It's not yet open to the public because they are still working on the implementation. At the protocol level, it is very much there, but you are right to point out that the advantages haven't been fully realized just yet.
It is very different than manually moving instances in the Fediverse, in my understanding. For one, it's totally transparent to the people that are following. All of your data comes with you. You don't lose your posts, your followers don't lose following you. I know Mastodon has at least recently gained account portability to some degree, but https://docs.joinmastodon.org/user/moving/ has some serious drawbacks that aren't present in the AT model.
Activitypub is the federation equivalent of an at-home 3d printer. It’s easy enough to understand how it works and do stuff with it. And very hackable. Bluesky is trying to be more like Firefox: it’s much more complex and built by experts to be well optimised for the problem it’s solving. But it’s much harder for lay people to understand how it works internally.