Several of those links seem to be agreements to set up relationships, like the fisheries one.

Yep - because Canada didn't "give Vancouver away," but set up a framework for resolving things in the future (like fisheries) so that they didn't have to go to court.

The declaration of rights has some cool stuff in it:

Yeah, these sorts of documents always have tons of interesting bits in the "Whereas" clauses and other non-operative provisions. Lots of history - but those terms don't actually provide for rights or obligations of the parties.

I like the nation-to-nation part. That means citizens of Canada get to deal with a whole other country inside of British Columbia now. One that by design doesn't have anything written down in terms of its laws.

Nation isn't the same as country. For example, we have tribal nations in the U.S. - but none of them are separate countries. They don't have militaries, they don't have enforceable borders, they don't have foreign policy or diplomatic relations with other countries. It's certainly a significant status, don't get me wrong. But it's not the same thing as having a separate country.