So, I took your advice and just went. And lo and behold, not only did my local store have the exact color and GB I wanted, they had lots and lots of other colors and configs, too. I don't know if they have every color and every config, but the sales guy said there wasn't much traffic in the store for the XR today. There were a LOT of people in the store for other things, though. And plenty of people buying other phones, too.
I don't know why iStockNow was wrong and even the Apple store site was wrong, but my store had plenty of inventory.
And, I have to say, the display is really nice. I don't know what people are complaining about. Sure, I get it that OLED is better than LCD and all that. But visually, this is a very nice display. I put it next to my X and compared the two, and I couldn't see a significant difference. Not $250 worth, anyway.