Totally agree. Google has a good platform. But they failed in adoption which is sad. Every time I look at Apple TV I can’t believe how bad the UI looks compared to Android and FireTV. And the new Android TV applied good learnings.
But as of the missing adoption they stopped investing in the development tools. Leanback is just crap and outdated and they never tried to replace it. So we are stuck with tiny user base and APIs.
For Fire: I agree: it‘s super successful, I am writing another FireTV app right now. But for most developers comparing to the number of phone users we are talking about the fraction of a percentage probably.