Custom Pop-up on BigCommerce platform

We are wanting to give a customized experience for customers that come to our clothing e-commerce store from different countries. When someone comes on our e-commerce store for the first time, we want them to see a pop-up from which they can select their country. On selecting their country, we want the currency of our website to change to their respective currency. We use BigCommerce as our e-commerce platform and they have a neat feature where we can redirect customers to [[login to view URL]][1] etc. to show visitors prices in their currency. Graphics of the pop-up will be provided by us. You will be required to make specific regions of the pop-up clickable.