Yay. I'm kinda sorta famous for something on the internet again.
My Pixelbook got bricked. What was really strange about it was that I had literally just gotten off my desktop to switch to my Pixelbook before getting ready for bed, and one of the last things I read on my desktop was a Reddit thread about the exact same thing happening to someone else.
I lay down, open my Pixelbook and 3 minutes later, it's all gone wonky.
Two units, different specs, identical failures within 24 hours of each other. Yeah, this isn't a hardware issue.
After a lot of hand wringing and finally getting around to buying a debug cable, I was able to find that something in their (pulled) update process appears to have broken the secure boot chain process of ChromeOS. Contrary to most reports, I actually wasn't on the Beta channel (some people affected were), the only thing I could have been accused of doing was putting off rebooting to apply the updates.
The second article really nails the point home: When Google sends software updates out to users that cause problems that they cannot recover from, why are customer service representatives still telling users "Nothing we can do, you're not in warranty" when they are contacted? This situation also shows just how broken warranty policies are, not much good 8 years of ChromeOS software updates are going to do when one bad update can brick your device in less than a year after your warranty expires.
Fortunately, those articles up there (thanks, duke!) and the information I've gathered from my serial console outputs may have finally turned the right heads. It still took two weeks, two articles and debug logs before someone started taking me seriously. At this point, I've been requested to 'discuss moving forward with an RMA" so the Pixelbook team can capture more data from my bricked Pixelbook.
So despite customer service's best attempts to sweep me under, turns out there actually was something of interest to the development team.
Hopefully I'll be privy to what they find.