Dunstans are a hybrid with good resistance. Any chinese tree will have resistance too. I know our Agway tried selling a few purely chinese trees last year, but they were still there in the fall. You can find 100% American trees online grown from seeds from parents with good blight tolerance, but there’s no guarantee on what those seedlings will produce.
I have about 10 american trees in my yard right now because I’m on the early list for those transgenic american trees from SUNY ESF. I need to have some pure american trees with it to create genetic diversity. Half of the nuts from the transgenic tree with carry the blight resistant gene and the other half won’t. I believe the transgenic ones are expected to be available to the public in a few years if they get the OK from the govt.