There is a lot of clamor about face unlock, but isn’t that an entirely software-based solution? The only additional hardware on the 8 to enable this is the purported ML capabilities of the new SoC, but it still uses just a single camera. I think all the magic that would enable this as a secure unlock is locked up inside the official pixel OS and not AOSP. It doesn’t seem like something GOS could adopt.
That said, I’m armchair-speculating here and could be entirely wrong.