I think Android TV is more strictly controlled by Google, as in you need to have permission to put it on your hardware. All devices that have it so far have been a "hardware partner" of Google. Cast compliance and all the other Google goodies that goes into it.
I doubt it'll come to these Android boxes anytime soon, unless someone builds a launcher to replicate the look.
Checked AmLogic website, There is no Google TV OS build for this series of processor. So I guess Google TV OS is out of question. bought the $69 Xiaomi Android TV mibox and love it. Unfortunately, there is nowhere to return the Beelink-GT.
Hope they will have android 7 for it soon and it then can be re-purposed as a desktop computer.