Comment by ABS

  Pixel device trees and other code used to adapt the AOSP release to specific (Made by) Google hardware was not released in a big change from precedent. Without the Pixel hardware repos (which include the device trees, driver binaries, and more), custom Android ROMs will have a hard time developing their OS updates. This might also have implications for security (vulnerability) researchers.

Some large organizations buy Pixel hardware for security properties and an ecosystem with multiple teams testing and contributing upstream. Their procurement teams may have opinions on this change.