>but that's different because that drive has those 256GB split over several NAND chips inside, so wear is spread out and shuffled around by the controller to extend lifespan. But when your entire wearable storage is a single soldered chip, I'm not very optimistic about long term reliability.

I thought wear leveling worked at the page/block level, not the chip level? On an SSD, if there was a failure of an entire chip, you're still screwed.