Google had introduced the company's Pixel devices quite recently, the Google Pixel and Pixel XL. These two handsets are the first true Google devices, as the company had designed both the hardware and software aspects of these two handsets, and HTC was hired to manufacture them. That being said, these two phones ship with Android 7.1 Nougat out of the box, which is the newest version of Google's operating system. The Google Pixel and Pixel XL do have some features that will stay exclusive to the Pixel line, but everything else will roll out to Nexus devices as well with a new update.
Speaking of which, Google's Camera app which comes with Android 7.1 is currently only available on Pixel devices, at least officially, you can install it on any smartphone which runs Android 7.1 Nougat though, which essentially means you can install it on Nexus devices which run the newly released Android 7.1.1 Developer Preview build. Anyhow, the Google Camera 4.2 comes with a new trick, you can take a photo using a voice command. In order to trigger this function, all you need to do is say "OK Google, take a picture', and that's it, the app will snap a photo for you. This can come in really handy if you're taking a group selfie and need to place a phone on the side somewhere while you join your friends in order to be in the picture.
Now, it's worth mentioning that you can trigger this function even if the Google Camera app is not open, which is great. Once you say the aforementioned words, your phone will open Google Camera and will start a 3-second timer, after the time is up, it'll snap a photo and save it to your gallery. In case you want to trigger the front camera for some reason, you can do that as well, all you need to do is say the following words: "OK Google, take a selfie", and the phone / app will do the same thing as with the main camera, but will use your front-facing shooter instead. If you'd like to make your phone snap a photo after some time has passed, you can say "OK Google, take a picture in X seconds", and by 'X' we mean a number of seconds (maximum 30). Do keep in mind that the last command will snap a photo with a front-facing camera for some reason, according to the source, but as the source mentions, this is probably just a bug, and Google will likely fix it soon. If your device is currently running Android 7.1 and you'd like to download this app manually, click on the banner down below, or wait for the update through the Google Play Store.