Teardown update: We removed that mystery Samsung RAM chip referenced above, and found a new IC underneath. This could be some custom Google silicon, but the markings are unfamiliar to us.

We'll work on tracking down its origin. Meantime, if you know more than we do, give us a shout in the comments!

The chip package is marked:

S4LV001A01 NGWF6YY5 1930—likely Google/Samsung neural core