backend php e-commerce with gatsby on wordpress

I want to make a small one-page online store. The site implies only a shopping cart with the product and its payment, as well as search. I would still like to implement authorization, but I am ready to give it up. At the front side, I want to use react with ssg from gatsby. Bit i am not good with backend and I want to use wordpress as cms. I had a problem at the architecture construction stage. I don’t understand how to integrate the front with the basket. Do I need to install a default theme? Or do I need to do the layout from scratch and the plugins allow me to integrate the shopping cart?

  1. I found this topic. Perhaps I can use it to implement the necessary functionality? enter link description here
  2. Perhaps it will be easier make it with elemetnor (which I do not want) or basic html+css+js?
    In fact, I have no problems with the layout of the front on the react. But I can’t figure out how to integrate backend into it using plugins. Thanks for the help.