Thanks for reaching out here in the Shopify Community to share your queries!
I’d like to share some info with you here on payment gateways available in Vietnam, and how you can set up your own shipping rates to match the requirements of your carrier of choice.
I’d advise you to spend some time looking into those options to see which might best suit your business needs before reaching out to some potential candidates to learn more.
Similarly, you should look into which shipping carriers are available to use where you are, and how much they would need you to charge to handle shipping your orders.
When you know which carrier you want to use and how much you will need to charge your customers, you can set up shipping rates in your Shopify admin so orders are charged correctly.