Hi there!
Thought I might post this here in the event it might help others get started developing Dash Replenishment prototypes using Arduino! There's a getting started guide, library, and a few example sketches that will get you up and running and initiating frictionless purchases using the Dash Replenishment API!
It'll walk you through setting up your amazon accounts, lwa, sns, and takes care of creating the API calls necessary to check subscription status, refresh token, initiate purchases, etc. Hope its helpful!
https://github.com/andium/AmazonDRS
--BCarbs
