It is highly unlikely that the Sony M4 Aqua will get an official Android Nougat update from Sony, given the fact that they’ve already announced that only the Xperia Z family of devices will get a taste of Android 7.0. Never mind that this midrange phone might actually have the chops to run Nougat. So if you own one, you will probably look to the aftermarket developers to see if any of them will try to bring Nougat to this device. Fortunately enough, some are trying.
An early build of an AOSP (Android Open Source Project) ROM based on Android 7.1.1 – the latest and greatest version of Android Nougat – has been made available on XDA for the Sony M4 Aqua. This is probably the closest that your device would ever get to having Android Nougat on it.
The first caveat is that this is an early build, and very far from being stable yet. Most of the features work, but there are some things that don’t – like the camera, speaker, and SD card storage. The author hasn’t even put up instructions for how to flash this, so you must know your way around flashing a custom ROM to be able to use this.
The second caveat is that Sony’s devices are usually full of DRM-enabled features. This means that if you flash a custom ROM, some of the device’s original features might not work – like Sony’s great camera quality algorithms, the stock audio player and enhancements, and other such things. But if you want to explore a bit, check out the source link below.