I emailed freeview plus about an ATV app and they came back saying only certified products get it, sounds like they get money from licensing it to companies and wouldnt make anything if it was BYO Device.
If anyone has the know-how or time it would be awesome if you could get the freeview plus APK and share it, if not ill ask XDA when i finally get an ATV device again.
The official stance is there's nothing really available per se for Android TV from our Australian TV providers. Sony does indeed have Freeview based apps for each installed on their TVs and they work quite well (I have a Bravia Android TV).
As for non-Sony Android TV such as Nexus Player, Shield TV etc. There's been some work on Whirlpool with getting the APKs for SBS OnDemand and ABC IView going - See here . Unfortunately there's nothing from Ten, Nine or Seven - you can side-load their apps and take your chances but they aren't great experiences.
Unofficially, we've heard rumblings of Android TV apps down the track - but they're quite vague.