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
Also, the opt-out of each number is only honored for FIVE years after which you need to opt-out again.