Not possible that would be breaking quarantine. Arriving in Canada by plane and needing to travel is different than arriving in Canada by land and trying to get on a domestic flight. You can verify but don't think you will be allowed to take a seaplane. Even taking the ferry creates problems for quarantine so you should speak to the ferry operators to see if arriving from the US and trying to get on a ferry will be a problem.
By using your words - you should do your research before you reply any of my post: In the ferry website, under Vehicles with U.S. license plates travelling on the Ferries, it reads BC Ferries does not have a mandate to restrict travel.