Easy Country Blocker App works for block the countries all over the world.
If you want to know about the countries which you blocked then you have to check blocked list in the app. There are two options first one is Available Countries and another one is Blocked Countries so you need to check in Blocked Countries.
It is important that you can directly check the blocked countries not even create any rule and all so this is easy to use app.
Install the app from here.
Shopify : https://apps.shopify.com/country-blocker-1
Bigcommerce : https://www.bigcommerce.com/apps/easy-country-blocker/