We are currently working on a shopping cart feature for SitesGPT. However, that feature won’t be available until our 4th quarter update scheduled for release in November. In the meantime, I recommend you use a 3rd party shopping cart that can easily be integrated into your site. There are several inexpensive and free options available. Here are some recommendations:
https://www.ecwid.com/shopping-cart
https://shoprocket.io/html-shopping-cart
Hopefully that helps. Let us know if you have any other questions.