Powering off Android Things
Usually, to power down an Android device, you do this via the power button of course.
You can also do adb shell and reboot -p.
But in Android Things, I don't see a way to shut down the device. If it is no problem, I'd love to just cut the power of my Raspberry Pi for this, but is that acceptable? Could it corrupt the SD-card?
Answer
Android (and by extension, Android Things) should have no problem with a sudden loss of power. The core operating system is housed in read-only partitions on the file system, so there is no risk of corrupting the OS from a failed in-flight write.
Also, reboot -p should still work if you wanted to use that in testing or development. Going even farther with it, you could connect a Gpio with an InputDriver that emits KEYCODE_POWER to add your own power button back to the system if you felt you needed it.