Hello,
The Apple Cash Terms and Conditions gives much more detailed information to clear up the confusion. I quoted some relevant sections below.
"you will only be able to use your Apple Cash Card at merchants that accept Apple Pay as a payment method. Currently, Apple Pay is accepted for in-store transactions with merchants that have payment terminals that support Near Field Communication (NFC) and within applications and on websites that have integrated Apple Pay as a payment method. Similarly, only other Users will be able to receive P2P Transfers from you."
"G. Assigned PIN.
You will not be required to select a personal identification number (“PIN”) for use in connection with your Apple Cash Card. If a payment terminal requires you to enter a PIN to complete a transaction with your Apple Cash Card, you should enter “0000” as your PIN."
Since it can only be used through Apple Pay and iMessage person-to-person payments the card number wouldn't be useful for us.
Apple Pay security and privacy overview - Apple Support
"After you authenticate your transaction, the Secure Element provides your Device Account Number and a transaction-specific dynamic security code to the store’s point of sale terminal along with additional information needed to complete the transaction. Again, neither Apple nor your device sends your actual payment card number. Before they approve the payment, your bank, card issuer, or payment network can verify your payment information by checking the dynamic security code to make sure that it’s unique and tied to your device."
I hope this helps.