I would like to know conditions when I can expect shipment_status field of the Fulfillment object is changed to "delivered". Which of the shipping carriers has Shopify integration and updating shipment_status field?
According to the https://help.shopify.com/en/manual/orders/status-tracking/customize-status-tracking#supported-shippi... it's only USPS, UPS, FedEx or Canada Post. Can someone confirm that?
Yes, that's right. The "Order out for delivery" and "Shipment delivered" notifications will only be sent out and updated when you fulfill orders that have tracking information from USPS, UPS, FedEx, Canada Post and DHL Express.
For other carriers, you will have to use an app like Shipment Tracking & Notify app, which will help you send tracking notifications to your customers. The app also allows you to have an integrated tracking lookup page, from where your customers can track their orders.
That is correct. For any other courier, you would need to use an app to track the packages. Shopify inherently works with these top carriers UPS, USPS, FedEx, DHL, Canada Post.