title_body: What are the differences between the FireOS Kindle App and the Android Kindle App?
upvoted_answer: To the best of my knowledge, the Kindle apps on both stock Android and FireOS are very similar. So you should have no bother with how your ebook is displayed within the application on those operating systems. 
  
  One additional point to add - You can get an Android emulator on your PC/Laptop and test out your ebook within the Kindle app on this emulated version of android.
  The link below shows off several Android emulators that you can pick from, have a read and see if any of those options are helpful to you :) 
  
  https://www.androidauthority.com/best-android-emulators-for-pc-655308/