There are CMS (Content management system) platforms like opencart, prestashop, shoppify and bigcommerce that support Amazon payment gateway service.
These CMS platforms provide ready to use templates wherein you can upload your products and start your e-commerce website. There is no back-end coding required as such. The Amazon payment gateway is already integrated in these CMS platforms. You can choose to activate it.
So almost all the sites on these platforms do have the option of Amazon Payment Gateway Service.