Android TV has gotten an app for Amazon's Prime Video, so if you've got an Android TV device or a TV with the technology built-in, you can open up the Play Store app and find the Prime Video app available for download and installation. To be clear, this is a release of Amazon Prime Video for Android TV as a whole as it has already been available as part of the NVIDIA SHIELD, so this is essentially expanding the availability to all other devices and TVs with Android TV baked in, which is good news for anyone who didn't have an NVIDIA SHIELD or some other type of device hooked up to their TV that bring them access to this service.
All of that said it's important to note that while the app is showing up in the Play Store it doesn't seem to be installable by all devices, as it is mentioned that the SHIELD as well as the nexus Player aren't able to install the app. Whether or not some devices are able to install it is still unclear, so for now it seems that Amazon may have just been publishing the app to the Play Store for Android TV devices and hasn't actually made it compatible with devices. If that's the case it's not clear when Amazon may open up compatibility to devices which may not have it, which could very well be all devices at this point still.
With Prime Video now available in the Play Store for Android TV, regardless of the fact that it doesn't seem to be available to install for any devices yet, Amazon is close to expanding the reach of Prime Video to more devices, having launched it back on Android for smartphones and tablets earlier this year, though it still lacks Chromecast support for streaming the app to TVs, something which Amazon may or may not end up adding at all. Nevertheless, if Android TV is your preferred method for watching videos on the big screen, then you can add Prime Video to the list of potential services you would use.