I'm not sure that the "Device Account Number" matters. As I recall from the presentation, that number changes with each purchase. And Goldman has promised (ha!) not to sell your information for marketing purposes.

But it's still worth opting-out of your Apple Card's virtual number.

The number is in the wallet app, ... > Card Information

I don't see the number exposed in Apple's UI, but I can definitely see it on my bank's website.

It's possible that this is an implementation detail and some banks do it without a unique card number...