APK files without having to root your device. You then need to find a tool that hijacks launches and allows you to open up and use. If you wish, you can find the Nova Launcher online as an. If that’s the case, there’s a strong chance that Amazon will take stronger measures to ensure people can’t use Android on Amazon devices.
However, be aware that if Amazon is starting to take action against launch hijackers, then people switching over to using an Android GUI are probably cutting into Amazon’s profits. Nova should now be active on your Amazon Fire tablet.