Hello Ying Gen,
Google Brillo it is not longer the OS for IOT for Google, at the moment the Brillo Change to Android Things, to be able to develop you need to be a register parner with Google, at the moment the i.MX6ULL Pico Board, it is supported and certified by Android Things.
You can find more details in the following link:
Supported platforms | Android Things | Android Developers
Have a nice day!