Is there a way i can get the data from the native checkout form in Shopify

Question

I am tasked with adding address validation into the checkout, therefore I am wondering if there is a way to get the user input from this native checkout form using LIQUID preferably or any other method possible. I have seen apps that do this, therefore I am assuming its possible at some level although Shopify doesn't grant open access to this part of their system, it's just rendered in from what I have seen. Any advice would be appreciated, thanks.