While our cart does request the buyer to specify their country and ZIP/postal code when items in their cart have Sales Tax/VAT enabled, we can only use that to calculate a tax amount which gets passed to checkout for their order.
Unfortunately, PayPal provides no way for us to pass non-shipping-related location details to PayPal's checkout site, and they have no way to provide such details (aside from residence country, which we include in our Transaction Log downloads) when they send the order data back to us with their IPNs confirming completed payments.
If you're going to accept checkout payments by PayPal, the only way to get a record of the buyer's location would be, as you've deduced, to enable Shipping/Buyer's Address for every relevant product.