Nexus 5X has exactly the same back camera, it takes pretty good pictures, software optimisation may have a lot to do with photo qualities as if you run LineageOS / CyanogenMod, you won't be getting as good photos for sure.
The problem with the Nexus 5X/6P is the poor build quality. While Pixel takes even better photos but the price? Execuse me, I am not going to pay AUD 1,296 for Pixel X 32GB (I got an iPhone 7 Plus 256GB for AUD 1,250 to replace the dead Nexus 5X for good).
Though guess Google's selling point on the smaller disk space is that it has unlimited cloud back-up for original quality photos & video.
Know you're locked in to their platform, but the ease of having photos/vids synced directly to Google Photos is quite nice with my Nexus 5, so feels like a big plus if I were to buy a Pixel and start shooting 4k video.
That said, still can't get over that high a price tag to go out & buy one.
The problem with the Nexus 5X/6P is the poor build quality. While Pixel takes even better photos but the price? Execuse me, I am not going to pay AUD 1,296 for Pixel X 32GB (I got an iPhone 7 Plus 256GB for AUD 1,250 to replace the dead Nexus 5X for good).