The newest little phone from Sony has been made more developer-friendly today. The Xperia X Compact has joined the Sony Open Device program, allowing the more technically inclined out there to build stock Android from AOSP for the phone. Sony has made the necessary code available for both Nougat and Marshmallow builds on the X Compact.
The Xperia X Compact was only made official a few weeks ago, and you can't buy it everywhere. If you do have an Xperia X Compact, you can unlock the bootloader and flash stuff to it. Sony has provided the necessary driver binaries for Nougat and Marshmallow, as well as basic instructions on building the OS from AOSP.
This is different than the Android 7.0 beta program, which Sony also makes available on several phones. That one includes pre-built beta builds of Android for certain phones. This is a more developer-oriented program. There's a GitHub project for the Xperia X Compact live now if you want to give it a shot.