If you want to manage devices that are currently not supported by balenaOS, then You will have to port balenaOS to that new device. In you example the android TV.
In this case, you would be porting balenaOS as Host OS for your android TV device. As per the links my colleague suggested above, you can follow the guides to porting balenaOS for your custome device(android TV). This balenaOS-powered device would then either connect to an openBalena instance or balenaCloud.