There is a way to install Microsoft Edge on Kindle Fire and its real easy.
1 Find a working Android APK for Microsoft Edge
(do not get the google play version)
2 side load it to your kindle fire
3 Install a good file manager from the App Store.
(es File explorer is good)
4 enable Non Kindle apps to be installed (if not already enabled)
5 Find your edge APK and install it to your device.
6 Log in to Sync your Edge browser.
Images coming soon