Amazon Fire OS is a mobile operating system based on Android, designed specifically for ARM-based hardware like Fire Tablets and Fire TV sticks. Because it does not run on standard x86 PC architecture and cannot be installed via traditional disc images, for it.
If you come across sites claiming to offer a "Fire OS ISO" for download, proceed with extreme caution: Download fire-0.3.5b.iso (DMZS-Biatchux Bootable CD Distro) fire os iso download
If you own the Amazon device for which the firmware is intended: Yes, it is legal to download updates. If you are trying to download Fire OS to reverse-engineer it or install it on competing hardware: This violates Amazon’s Terms of Service. However, since Amazon doesn't offer generic ISOs, the point is moot. Amazon Fire OS is a mobile operating system
is a mobile operating system developed by Amazon. It is a fork (derivative) of the Android Open Source Project (AOSP). Think of it as Amazon’s heavily customized version of Android, stripped of Google Mobile Services (GMS) and instead integrated with Amazon’s ecosystem: Alexa, the Amazon Appstore, Prime Video, and Kindle. If you are trying to download Fire OS