[Ned Scott]

I had high hopes for Kodi on Android, and specifically FTV. I understand that the problems/issue stem from lack of platform consistency, not Kodi development gaps.
Thus, while I use ftv on my kids TV, I have moved back to Windows for the home theater.
It seems that, like it or not, the Windows platform has the most features, least problems, and least tweaking needed to make it 'just work', especially for power users of home theater and automation.
So, if you need pass through... Use Windows and be happy.

Reach out to MrMC on his forum and ask him what the current status is on that. The MrMC fork is basically Kodi v16 but with the v17 audio system, and the Fire TV platform is a major focus for him. If there is a way, he will find it. If he finds it, SPMC is likely to add that into their fork (if, for some reason, it is not accepted into vanilla Kodi).