Camera NX brings Portrait mode to the original Pixels, Nexus 5X, and Nexus 6P
The Portrait mode in the Google Camera app has been a Pixel 2 exclusive feature with Google claiming that older Pixel and Nexus devices do not have the necessary hardware to get the right output. However, an enterprising developer, Charles Chow, has created a mod named Camera NX that enables owners of Pixel, Pixel XL, Nexus 5X, and Nexus 6P to benefit from this functionality.
Chow's Camera NX takes a burst of photos to create a depth-of-field look unlike the Portrait mode in the Pixel 2 Google Camera app. The mod implements the zero shooting lag HDR+ (ZSL-HDR+) functionality that is found in Google Camera v4.2 and works only in the Pixels, on older Nexus hardware. The mod suffers from a limitation of being able to create depth-of-field looks only when it identifies a human face while the camera app of the Pixel 2 can create it with almost any object. Chow claims that the mod has been tested to work on the Nexus 5X and should, therefore, work on the Nexus 6P and the older Pixel series.
The app can be downloaded from the developer's blog and sideloaded onto the phone. Do have a look at the mod's thread at XDA forums before installation for any potential issues, especially on custom ROMs.