Fetch cart data

Site URL: https://www.1924.us/

Does Squarespace expose cart data? I see the shoppingCart property in the JSON data, but it's otherwise empty. And I don't see anything in the developer docs about the cart either. I know the cart page itself is rendered via React, and they include the cart JSON data within the HTML on the page, but it's not available to fetch from anywhere else on the site.