Currently Sudoku Helper is available to Android devices accessable through the Google Play Store.
There are two versions of Sudoku Helper on the Play store. A fully functional free version that you can try and a very cheap paid version with a few extra bells and whistles.
I have tested Sudoku Helper to work on a Kindle Fire. However, Amazon doesn't put the play store on thier devices. To put apps on the Amazon store costs $99 a year. While this doesn't seem like a whole lot of money, I'm waiting so see if Sudoku Helper is decently recieved through the Google Play Store first. If playing on your spiffy new Fire is something you'd like to see, then get all your friends to buy the paid version and tell all their friends how awesome it is. You can also send me an email letting me know just how much it would mean to you.