Google is offering refunds for Pixel audio issue devices it seems, as one customer who owns the Pixel XL has received an email from the Google Store support team stating they would issue the refund for his device. To get a refund, you would need to return the device and any accessories that were ordered with the purchase, and after receiving it Google would refund the purchase. Naturally, this would probably be on a case by case basis and Google isn't just going to start handing out refunds to every single customer before they investigate the issue, but according to the individual who received the email Google's solution to correct the problem was to refund the device purchase instead of sending out a replacement device.
With replacement devices, which should be available to anyone who purchased the protection plan along with their new Pixel or Pixel XL, these have the potential to be refurbished devices. That being said, a refurbished device has the potential to carry along with it another issue if not the same one as the original device, and they may end up completely fine with no problems at all. What's interesting is that Google seems to have jumped straight to issuing a refund instead of suggesting a replacement or trying to work with the customer to fix it, and while this is not necessarily a bad thing as you would be able to simply buy a brand new device again, it could come off as Google not having faith in their product, at least to some. That being said, there are plenty of happy Pixel and Pixel XL customers out there with no issues, and with the amount of marketing Google has been doing with these phones it appears they believe strongly that they have an excellent device to offer.
The audio issues in question date back to the end of October where they were initially being reported on the Google Product Forums. The most recent response from Google as of December 19th mentions that they were still investigating the problem. A couple of days later, a post on Reddit offered up details on a workaround for the problem that would allow users to give their devices a temporary fix. While it is unfortunate that there is still no proper fix for the audio issues, it would seem that Google is at least willing to refund customers. Whether or not that's perceived as a good or a bad thing is ultimately up to each individual, but if a refund is what you've been wanting, contacting Google Store Support might be a good course of action.