One neat thing Amazon are doing with this product, which I hadn't considered as an "internet of things" option, is making each unit of hardware order a single supplier's goods. All the example buttons say "Tide" or "Bounty" or "Gillette" or "Olay" right on the button - all Procter & Gamble. And the other goods pictured [1] are all brand-name goods with fairly big marketing budgets.
In the jargon of the grocery industry, this means the buttons can be "supplier funded" - Procter & Gamble probably pay Amazon a reasonable portion of the cost of the button, as a marketing method.