What does it mean for Android Things (former Brillo) project? Intel Edison and Intel Joule were ones of the few supported boards.
Given that you mention it, from a hobby developer perspective, I would rather pick W10 IoT, because at least Microsoft does offer proper support for C++, including easy integration with .NET, unlike the dev experience with the NDK.
In the context of my comment, of going to production, the Pi Zero W has the problem of availability / supply chain. So if you plan to manufacture a lot of devices, not only are they hard to get, you get low-volume pricing instead of discounted.