Following the release of the first Android P Developer Preview today, you may have wondered why the only devices you can install it on are the original Pixel and Pixel XL, as well as the Pixel 2 and 2 XL. It's simple: Google isn't brining Android P to its earlier devices, including the Huawei-made Nexus 6P, the LG-made Nexus 5X, and the Pixel C tablet. The Nexus 6P and 5X launched in 2015, and before the second-generation Pixels Google's promise has been to deliver non-security software updates for two years since release. Huawei Nexus 6P Those phones got Oreo, but when P comes out...
Source: https://www.gsmarena.com/android_p_isnt_officially_coming_to_the_nexus_6p_nexus_5x_and_pixel_c-news-29984.php