Upload custom product to WooCommerce Cart from App

I’ve created a C# Windows client application to create designs of various types, and would like to upload the designs (PDF/Png/etc) to a WooCommerce cart to allow the customer to order professional prints.

How to achieve this in WooCommerce?

For instance, first upload the design to a remote folder accessible from WooCommerce, and then view the cart in the web browser by specifying a custom URL with product ID, custom design ID and thumbnail ID.