Once one has used the development kit to prototype a device, how are ACK Modules purchased for inclusion in a product? There is an email address to write, "to discuss one's product", but after a month there has been no response. I assume that one purchases ESPRESSIF modules that come preprogrammed with Amazon firmware and an identification number that will be registered when a customer connects the device. It seems a bit of a scam to promote purchasing a development kit if production ACK modules are not readily available.
UPDATE: Winding through the documentation appears to provide most of what would be necessary to provision a module, other than the steps that require Amazon approval. My approach was to find out the cost first, rather than developing a product and hoping that registration for each product was affordable, and that Amazon would approve the product.
So, the real questions are, what is the registration cost for each device sold and what are the criteria for a product to be approved? Sadly, that must be some kind of Amazon trade secret since it is so difficult to obtain. As a small business, sinking a lot of time and money into a project without knowing the Amazon cost for each unit or whether one will be able to get Amazon approval, is unsettling. Given that Amazon does not guarantee to answer the email address given for just such questions, that makes evaluation for proceeding with a project for low volume products difficult.