you can add a shipping country filter to the delivery orders page by creating a new custom filter in the "Delivery Orders" view. Here are the general steps to set this up:

1. Go to the "Inventory" module in Odoo and navigate to the "Delivery Orders" menu.

2. Select the "Delivery Orders" view and click on the "Edit" button.

3. In the "View Editor" menu, navigate to the "Filters" section.

4. In the "Filters" section, you can create a new filter by clicking on the "New" button.

5. In the "New Filter" menu, you can set the filter's name, such as "Shipping Country" and set the filter's type to "Selection."

6. In the "Selection" field, you can set the filter's options, such as the different shipping countries that you offer.

7. In the "Filter" field, you can set the filter's conditions, such as the shipping country of the delivery order.

8. Save the filter and activate it.

9. On the delivery order page, you can now filter the delivery orders by shipping country.

Please note that these are general steps and the exact steps may vary depending on the version of Odoo you are using, and also you may need to add the country field in the delivery order model to be able to filter by it.