Gatsby / shopify-buy Possible to prefill address on the Checkout page?

Hi! Since the regular plan of Shopify still cannot transfer account details from the custom storefront to the checkout, we need to find a solution for making it people as easy as possible. Right now they need to login again, to get their address filled, and this is not what I want. Would it be possible, and how, to get the address data transfered when the user clicks on the checkout button? I did read something about it here (https://github.com/Shopify/storefront-api-examples/issues/80) but I am not sure if this is really possible.

Thanks!