My name is Alissa, I am part of the Guru team at Shopify.
You absolutely can sell products to a USA customer base from outside of this specific country. You can sell worldwide if you would like! ?
One thing to keep in mind, is depending on the country you are selling from this will determine the payment gateway you will use to run your checkout. I recommend to take a look at this list, to see which are available for your country!
If the products you plan to sell could be higher risk or have issues with customs regulations, I would reach out to your local authorities or post office to ask about international shipping requirements/regulations just to cover all bases!
To specify which countries you want to ship to, all you need to do is create a shipping zone for those areas under Settings>Shipping. Any region not added will be ineligible to order from you!
Feel free to reach out to Shopify Support if you have any questions! We are always here to lend a hand. ?
All the best,
Alissa F | Shopify Guru