Would that be handled like most certification processes where the business applies for certification and pays a fee? Or where Amazon randomly selects vendors and tests them, the later seems like it would be more costly than sourcing the products yourself.

IMO the second one would be almost impossibly difficult at Amazon's scale. It would have to be the first. And of course that means setting the price so that they can handle the amount of incoming requests, which means it will eliminate some smaller groups. But i feel like if i were a creator of something, i'd want to pay the money to get it "certified" rather than amazon copy it.