No, by definition we only see the observable universe like you noted, but most people assume there is more out there beyond it. In fact, by the Copernican principle we should assume there is more out there, otherwise we happen to find ourselves exactly in the center of everything and can see exactly as far as light could have traveled in the known age of the universe.

The title is a little unclear, but I read it as the most distant known supermassive black hole. This is the farthest one we've detected, but we can assume there are further ones (even some that may still be detected by Webb in the future)