Android Things is cool to reuse Android knowledge, but one is better off with a board that supports GNU/Linux directly, as there is support for whatever programming language one feels like using.

Ehh, not always. It is often best to avoid a full OS in favor of something with less complexity. Android Things and Windows 10 IoT are attractive for this reason, among others.

Android Things and Windows 10 IoT are a full OS.

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.

Things runs fine in RPi3. I can't imagine why you'd use this awfully supported board over that one.

Well, a system-on-module is advantageous over a full board like the RPi3 if you want to go to production. But there are more SOMs supported, apart from the Edison and the Joule.

There's a module version of the Raspberry Pi.

Well, the parent commenter was talking of the RPi3. Android Things doesn't support the Raspberry Pi Zero W.

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.

The Zero wasn't mentioned. There is a Raspberry Pi 3 compute module, and I suggest you look that up if you think I am talking about a Pi Zero.

Ah, I see! Not sure if you're the same user as the ones above, but the Compute Module 3 doesn't come with networking chips, so it's a no-starter for Android Things.

The RP3 compute module gets plugged into something else. That something else is free to have Ethernet.