Hey, there.
Dallas here from the Shopify Social Care Team.
Great question and I am happy to say that I think I have some options that would work well for you. Rather than organizing your customers by tags I think it would be better to organize your customers by postal code orzipcode. In order to achieve this you’re going to need to get an app. Each one has different features, but a quick summary of each app that I think could work for you:
This app would be if you wanted to block customers from your site entirely.
This app would allow you to create different pop-ups & banners that only visitors located in certain areas could see. It would detect your visitors’ locations which you can filter by country or zipcode and then depending on their location they would see/would not see the popup.
ie. If you are restricting visitors from Canada, all Canadian visitors will see a pop warning with a message that your store does not offer shipping to Canada. Unlike Easy Country Blocker, this app will not restrict these visitors to access to your site and continue browsing. If you choose to install this app, I do recommend to also install Easy Shipping Restrictions, in case your visitors missed the pop-up.
This will prevent customers from accessing specific products until their zipcode is compared against a list of areas that you have approved. It will add a field on the product page that will be used to verify the zipcode/postal code
My fourth and final suggestion is the Locksmith app. This would basically lock the page via password. If they enter one of the passwords you create then they will be able to access the page and add that product to cart. If you wanted you could make the passwords a list of all the countries that the product is available in. Then you could ask them “what country are you located?”. If they type the country that matches your list of approved countries then they will be able to enter the store. I hope that makes sense.
Based on my understanding of what you’re looking for I think these would be the best options in order to achieve this. Please feel free to ask me any further questions after you have a chance to go through the options.