Creating a free Google Sites online store with a free payment gateway is a straightforward process. First, register your business with Google Sites. This will allow you to access the Google Sites platform. Next, create your store by customizing the Google Sites template. This includes adding products and their descriptions, setting up prices, and creating shipping options. You will also need to set up your payment gateway.

To do this, choose a free payment gateway such as Stripe or PayPal. Once your store is created, you will need to verify your business with the chosen payment gateway. This usually requires providing identification documents and bank details. After successfully verifying your business, your online store will be ready for customers.