Do I need to use credit cards from outside the country?

if you want to maintain your credit score from outside the country, then you'll have to follow certain procedures. It is better to do that because why will you make your hard work go into vain?

Check this out:
https://www.debtconsolidationcare.com/blog/how-to-keep-credit-profile-active-outside-usa.html

If you want to come back to the country in the future, then you should use credit cards from abroad. You should do a few credit card transactions and pay all the bills to maintain your credit score.

Yes, you can maintain your credit score from outside your country.