Google is reportedly offering Pixel XL devices as a replacement to those with defective Nexus 6P phones. The select Nexus 6P devices who have a faulty battery comes under the process of RMA even if they are out of warranty. And this consideration of replacing the Nexus 6P with Google Pixel XL is only for the people who bought it online from Google’s Store. They’re shipping the Google Pixel XL in select countries, including the USA and Canada. A few users in the UK have received a Google Pixel XL and selected few have received a Nexus 6P as its replacement. If you are in Australia, Google is sending new Nexus 6P devices in return for the defective Nexus 6Ps.
Just an FYI, Google is sending the replacement phones first and then asking for the defective phones. It is doing so by charging the new phone on your credit card. The amount will be refunded once the defective phone is received by them.