@Mtncj yes here in Canada we can buy nanking cherry in 3 colours. It’s more about ornamental appeal than quality of fruit. The fact they ripen early is the only reason to grow them. You can graze 15 or 20 berries and then the sour catches up to you. A decade or more ago most Canadian nurseries recommended nanking cherry and western sand cherry as plum pollinators. Today most recommend a native plum(Canadian or American). They tell you to let a branch grow near to the ground so it will flower at the same time as the earliest plums. That doesn’t work that well so my nanking cherry is safe. In your zone you should be able to grow many early blooming Japanese plums, so no real need for a nanking cherry. You mention Brookgold plum. It is difficult to buy a Brookgold that has golden plums. Many including myself get red plums on our Brookgold. I question whether Brookgold is not a stable variety or whether some bigger players have just messed up their scion source.