Google just dropped support for the Nexus 5X and 6P, for unknown reasons. I hate it. Now I have no options left. (I need a device that will get android developer previews)
By the way you can get a custom rom from here: https://forum.xda-developers.com/nexus-6p/development
Some of my users are on Pixel devices and will get Android 9.0 the day it is released, while in best case, the source code only drops a week later. So assuming it takes me 10 minutes to fix all bugs, my app might crash for a week.
Realistically, my apps would be at least a month unusable.