Even a product replacement won't fix the issue, so good call on that.
I've had this ongoing sound not working before I sent my device in twice and that was in Feb 2018 and the issue still remains.
My issue was a bad screen burn-in, contacted Google and they sent me a refurbished Pixel XL since it was under warranty. Had the refurbished Pixel XL for 1 week and the speakers started to crackle and the random sound dropping issue was still present. Contacted Google again and they were going to send me another refurbished device but I ask kindly if I could just get a new one and they agreed I could. 2 months later, I still have issues with random sound dropping.
I've always been a Google whore ever since the Nexus days. I've own the Nexus 4, Nexus 5, Nexus 6 & Nexus 6P, when Google came out with the Pixel device I was shock by the price tag but I bought the damn thing anyways because 2 things I can't stand in a phone, bloatware and no damn updates. The only devices in the market that don't have bloatware and give timely updates are the Pixel & iPhone, well I ain't gonna buy another Pixel again because even the Pixel 2 has issues and it appears Google could really give a rats ass about this sound issue, so that leaves me with 1 choice, a ****ing iPhone.