Recreate External Web API using fetch requests

We are wanting to utilize a 3rd party web api. The task will be to recreate it using fetch calls. Attached is the code we have already written. The problem we are facing is that when calling the first fetch function incorrect customer data is returned. To mimic, simply go to the the root domain listed in the file, then open Chrome dev tools and call each of the fetch functions. The result should be items added to the shopping cart and reflected in the UI upon refreshing the page. Success equals navigating to the host domain and leveraging the fetch requests to add items to the cart automatically. This code will then be used in a custom web view in a React Native app. If successful, additional opportunities are available for similar tasks.