Idea is that eventually others will be able to build atop their protocol and set up different “appviews” as they call them as well as relays and personal data servers. As I understand it, “appviews” may be viewed similar to what Lemmy and Mastodon are to ActivityPub, different ways to view data passed through ActivityPub.
Right now I think Bluesky may be the only such “appview” for their protocol parsing data from their relay, but the idea is you could spin up your own personal data server and maybe also your own appview, or choose from whichever may eventually exist, and that would be like your own “instance” connecting you to others via the appview parsing relay data.
So in other words, sort of yes to your first question, and it’s sort of because right now there’s only one AuthTransfer relay at the moment and that’s Bluesky, but the idea is that others could be spun up, allowing more independence from Bluesky as a company.