Side and rear door weatherstripping for Dodge vans has never been available in the aftermarket. Front doors? Yes. I bought the second to last set of side barn door weatherstripping in the Dodge dealership inventory about ten years ago. I should have bought the last set as well.
You can try plumping your stock weatherstrip up with silicone injected inside, or using stick on foam weatherstrip, or find some other creative solution. Good luck!