Depending on the merchants terms and conditions, usually you cannot use the gift card outside of the country of purchase unless it states it can be used internationally. You may be able to purchase from a US based merchant then have it shipped internationally, but again that would depend on the merchant.
Additionally, if you were wanting a solution for end users to check the balance of a card, you would have to be issuer of the card. The merchant you are working with to purchase giftcards may have their own solution for checking balances.
If I misunderstood your business case, please let me know and I can try my best to help.
You can find a Visa Partner here: https://partner.visa.com/site/partner-directory.html
that can help with your use case.