Android TV devices are supposed to have all the functionality of a Chromecast, since they also act as Cast targets. However, there are still some quirks that remained unresolved. Netflix integration with Google Assistant went live nearly two years ago, allowing users to say "Hey Google, play The Office on Netflix" (or something to that effect) to an Assistant speaker, and the content will start playing on their default TV.
For whatever reason, this never worked when an Android TV was the target device. Assistant would just respond with, "Sorry, I can't play Netflix on Android TV yet." To make matters more confusing, the same exact command works on Android TV's own Google Assistant. YouTube and Google Photos work as expected.
Google confirmed to us that this issue has finally been addressed, and the fix should be rolled out to 100% of units this week. So if you happen to pick up the new Mi Box, you'll be able to cast Netflix to it with voice commands as if it was a Chromecast. We're in the process of checking if this works with other video providers, like HBO and CBS.