Hi, I am Taiwanese and I live in Taiwan, I'm doing print on demand with Printful.
I design koala pattern t-shirt and I only want to sell them to Australians.
Questions: how do I set up my store to only sell to Australians?
You can create a single shipping zone for Australia and add the rates only for this zone. When customers from other locations comes to checkout, they won't be able to complete the order as it will show an error at checkout mentioning "We don't offer shipping to California (for example)". See the image below.
Hope this helps!