i merember that nostr:npub1lr25yphwccgprzcmmghcxmvul5yg59fypmg3wgeh80w8ej5hnuaq42lf8t had a modded nfc card he'd programmed to send his npub to any device that uses it, when i bumped into him at bitcoin atlantis

perhaps you should consider modifying the purchase ordering to allow users to ask for an npub to be burned in and locked for them, and maybe even add their npub and display name to the back in the style of a credit card (npub as the card number part) - i have a xapo card, mastercard, yes, and on the back is where the actual card number and expiry etc are located

maybe even putting a unix timestamp of the oldest note you can find from them too... in place of expiry and CVC