Were you able to get help? If not, let me know. The hardest part in your case will be building the user-interface. OpenAI only provides a very simple interface.
Did you consider using QNAMaker? Also straightforward and owned by Microsoft (they also bought a license in OpenAI). Open source chat interfaces are available and maintained by a growing community.
Let me know if you need more info about chatbots and Shopify
Hessel - Botz4U