Soooo...thanks to this little adventure, a Nexus 5X with which I was perfectly happy is now very close to being a doorstop. Irritating since I would have gladly used that handset at least one more year, and this was a lousy time to be spending new phone money. But a Google Pixel (gen1...that's "1" as in "has 1 headphone jack") arrived a day early and is now running in its place.
Conclusion: I like it. I like it a lot. Not only does it have a better fit-and-finish than the 5X while losing the 5X's camera bump, the 5.0-inch display means it's also just a hair smaller than the 5.2-inch 5X at the same 1080p resolution, and it fits my hand where the 5X felt a smidge large. Since I'm exactly the median height for American males and not a big build, the 5X was also a smidge large in my pocket. The UI is more responsive, applications perform better and are less likely to be evicted from memory during task switching, and the built-in-speaker is considerably better than the 5X. It also included a USB-OTG adapter and premium-qulaity C-A USB cable along with the C-type charger and C-C cable. At least Google got that part of the high-end pricing experience handled correctly.
I seriously considered the Pixel2 since I could direct-order that from Google and get the warranty whereas this was a sealed NoS unit from a fulfilled-by-Amazon seller, but the 2's higher price and lack of headphone jack (yes, I use it now and then) represented a fatal twofer. A pity Google abandoned the Nexus pricing model, as this unit (perhaps with cost savings such as a composite case and bonus USB accessory delete) would be a perfect midrange market killer.