Flutter Backend & Frontend Expert

I am looking for a Flutter specialist to carry out tasks both in the backend and in some aspects of the frontend. This is an information logging app that uses reference products connected to Shopify. The customer selects certain products and, using a form within the application, registers and sends the data to create a new "customer" user, using their email address as a reference. All this is done using API (GraphQL) for communication between the application and the store in Shopify. Frontend development is almost complete; I just need to fix a few points, while the backend flow is clear for easy understanding of the work. I will provide a detailed explanation of the process to the selected candidate.