So, notice Graphene OS was able to port Android 16 on all the supported devices (from Pixel 6 up) basically within a week without device trees already, without the early (OEM) access to the release.

It's a big inconvenience but not a showstopper for them. Pixels are still viable.

The only blocker with pixels would be if they stopped allowing OEM unlocking or relocking (which is a must).