It's actually quite clever in a way, on the part of Harry and Meghan.
From the moment a photograph is published of Charles with Harry, or Harry and Meghan, or Harry and Meghan and the children, Meghan's As Ever line will take off. People in the US will pay for the royal "sprinkle" (you can't get Highgrove products here), and the American market is all Meghan cares about (she certainly doesn't care for Harry's family or the UK). And, she would defend herself by saying she started As Ever while still in purdah, totally no-contact with the RF. Harry will say that Peter advertises milk in China; this is Meghan's own hard work starting an entirely new line from scratch by herself. It came first, not the extra and new-again royal pizzaz. I imagine this is what Netflix is holding out for.
It's gonna happen, unless Charles and the men in grey ensure no such photos ever reach the public. Personally I don't think Harry wants to return to the UK full-time, and Meghan absolutely would love never to set foot in the country again unless she's getting paid for it (paid a lot). So Harry could easily commit to not monetizing the link in the UK, but we live in a global world.