Is there an online store CMS for one product?

Question

CMS

The main requirements are:
1. Connecting the QIWI payment module, as in the deer.io store (payment is made through a money transfer with the obligatory indication of a note to the payment, and not by invoicing.)
2. Custom fields. So that the user can specify one information in one field, another in the other, and all this information was sent to my mail.

Answer 1

there then make it by God 1 day without cms there will be at least php

Answer 2

Make a landing page (landing page) for a product with the possibility of ordering.
Might be worth a look here - wix.com