Here is how I have my Fire HD 10 (2017):
Fire os 5.6.00
I changed build.prop build no to 987654321 in order to stop ota but keep updating the amazon apps. ( works flawlessly )
installed root, busybox, xposed ( all working great)
set up kernel auditor to change my SELINUX to permissive on boot.
( I did not have launcher hijack on at all )
here is what i did to get it to work.
1. First install nova launcher as normal.
2. Connected to pc via adb and:
2a. adb shell
3. then I ran this.
3.a pm enable com.teslacoilsw.launcher
you will see it say that the package has now been enabled
4. Then i ran this to disable fire launcher.
4.a pm disable com.amazon.firelauncher
you will then see that it says the new state is disabled
I hit the home button and poof it magically worked. I even rebooted and it worked directly after reboot as well. Home button works as it should and all the functions of the launcher work as well.
Hopefully this works for others.