Sony's Xperia Z3 is one of the first non-Nexus device to support the Android N Developer Preview. It was previously rumored that Google would allow other manufacturers to begin testing the software, and that appears to have proven true. You will need to flash the first image (of Developer Preview 2) and then Sony will push future updates over-the-air to the phones.

Xperia Z3

From Google's announcement

The Xperia™ Z3 joins Nexus 5X, 6, 6P, Nexus Player, the Pixel C tablet and General Mobile 4G (Android One) in giving you an early look at the next version of Android. Sony has been working closely with us to bring you the N Developer Preview on Xperia™ for early testing and development.

To get started, you can download the latest N Developer Preview from Sony (currently Developer Preview 2, available at the link below) and manually flash it to your device. You'll then receive future Developer Preview updates over-the-air, direct from Sony.

So, if you happen to have a Xperia Z3 laying around, and want a taste of the latest operating system before it is officially available to everyone, you can give it a go now.