I've three similar numismatic mobile Android apps ([login to view URL]): Euro, UK and US coins.
Task 1: Upload a new key (I've got it already from the Google Play) for Euro app.
Task 2: Apps are connected to the web-site and should be updated manually. I am creating a new build and uploading it to Google Play every time web-site gets new coins. There is an infrastructure on my PC (Windows 10) that helps me to do so (I am not a developer).
The goal is to make the whole process automatic. Whenever new coins are added to the web-service, mobile apps are getting updates. Please, provide shortly your idea of how you are planning to implement it. There is a developer of the web-site who may help on the server-side to prepare all the needed info.