As for the cart, it should show users the potential delivery time depending on the region, estimates from different shipping providers, etc. The cart should also be able to calculate any taxes, handling fees, customs, and duties, etc.
If there are any location-based restrictions, it should inform that the user too. Ultimately, features like these prevent any compromises to customer satisfaction.
Finally, if there are any special discounts according to the region, customer or quantity, the cart should be able to calculate those too. For instance, if there is a special promotion in a particular area for a holiday or an event, your
cart should be capable of handling it.
All the carts on the site should reflect any region-based discounts. These include the mini cart (usually in the header), the add to cart options, and the full-blown detailed cart page.