Isn't it what Amazon Market do? Downloading the apk, and notifying you that an update is ready? But you have to allow untrusted sources installation in the sec

Isn't it what Amazon Market do? Downloading the apk, and notifying you that an update is ready? But you have to allow untrusted sources installation in the security menu, and still have the installation screen (left screenshot in the article). I don't see a problem, some games are downloading and updating their files too. If you don't trust the app, use FB website.