For games, the technical difference is quite big though, and you'll probably end up releasing on iOS first.
My game was developed on Android. The original demo's been downloaded over 100,000 times without many complaints so I THINK it should work on most devices. I need to convert to iOS next. Technically it should be fairly simple but going through the hoops with Apple however...I have no idea.
NOTE: The stats for the Kindle app store are a bit skewed as Amazon ran a lock screen feature promotion for the app. The other services have never run a feature promotion for the app.
That is a huge number for Amazon! Did they simply choose your game randomly to feature or did you have some sort of partnership?