At least in the US Keystone does allow shipping to PO Boxes.
The data in the OP is based on what info I got from the customer support of all those companies. Does their online shop allow you to complete the purchase after selecting a PO box or is there an error or other type of notification that hinders it? Do you know what carrier they work with in the US? The information I got off the Ledger support team was that their packages in the USA are shipped via DHL, and they don't deliver to PO boxes. So it's a restriction set by the carrier company and not the device manufacturer. It went through with no issues. Since they do sell through Amazon here in the US I wonder if they are just using them for fulfillment here. Would cut down on a lot of work for them in terms of logistics.
Does this link work for you? https://www.amazon.com/stores/page/0360EBE5-E20C-45DC-836C-59573EAE62F5
Also, they use opennode.com for BTC payments and Coinbase Commerce for altcoins and also BTC.
I got redirected to Coinbase Commerce when I imitated a fake purchase just to see where it would take me. It's the first time I hear payments are also processed by opennode.com. Are those Lightning payments maybe or is it a geographical thing that determines which payment processor a customer is redirected to? Lightning or onchain.
When I go to pay this is what I see, you have one option for Coinbase Commerce and one for BTC:
When I click through the BTC option it takes me to an opennode link, to pay a shopify cart.
So it could be they are using different providers depending on where the customer is coming from, could be they changed the day after you spoke to them. Or, it could be their customer service person who you were dealing with was wrong.
Probably not that big a deal in terms of security / privacy now since they are using a 3rd party cart we don't know what else is being captured. What information is shopify getting and keeping?
That should probably be another column in the chart, self hosted cart or 3rd party.
-Dave