The Nexus 5X and 6P are the latest handsets from Google to sport the Nexus name, and they mark a lot of Nexus firsts. One such first you might not have been aware of comes on the post-purchase support end of things: Google isn't handling warranty or support claims for the Nexus 5X or 6P. If you contact Google about a warranty or other support claim on your shiny new Nexus, even if you purchased the device from the Play Store, they will send you packing to LG or Huawei.
This is an about-face for Nexus phones, which Google has previously supported on both the technical and warranty end of things explicitly. So, if your Nexus 5X suddenly develops a strange issue with its display, Google won't be the one helping you - they'll send you along the LG. Same if your Huawei Nexus 6P develops a spontaneous glass crack - you have to go through Huawei, Google's not going to send you a freebie like they had previously with the Nexus 5 and 6.
Contrast the above with the Nexus 6. The reason for the change is likely to reduce costs on Google's end and, theoretically, make manufacturers directly liable to device owners instead of holding Google accountable for defects or other problems. But it's probably mostly a cost thing.
The one exception to this rule may be Nexus Protect, which is only available in the US and Canada at this time. While Nexus Protect is technically an extension of your existing warranty, not a replacement for it, we've spoken to Google and they state quite clearly that if your device experiences a hardware failure or defect in the first year of ownership and you purchased a Nexus Protect plan, you can go through Google for the manufacturer warranty claim process. Google did not elaborate on what that entails, but it sounds to us like Google may handle some of the more tedious aspects of the process for you. Until someone actually submits a warranty claim via Nexus Protect, though, we just don't know how the system will work.