PO Boxes are tied to specific post offices and/or ZIP codes. There are almost certainly hundreds of not thousands of addresses that are PO Box 271 in the USA. What GP wants AIUI is a single mailable id that can be mapped to any delivery point in the area that the USPS serves.
is that what a PO box is for? You can give out your PO box instead of an address.
unfortunately, the mailing address is sometime (ab)used by parties that also want your real address.