Android common kernels(ACK) are downstream of Linux kernels with so many patches which are not there in the Linux kernels. So Linux having short 2 years update cycle doesn't have much implication on ACK.

That's a disappointing answer if it is really the case. One has to question why they can't forward port their changes for a handful of years.

They have been been upstreaming patches to the kernel. In fact Android works with a stock Linux kernel now.

For the nonexistent Pixel 8? Or are you referring to running on a Pixel 6a, for example:

https://wiki.postmarketos.org/wiki/Google_Pixel_6a_(google-b...

This device is marked as not booting.

I'm stating a general fact that the patches in ACK are not needed for Android to work.

Many past Pixel devices, which are still in support, cannot seem to run a mainline kernel.

ACK is built on top of the LTS, so it done impact how long a version of ACK exists.

The Fairphone is aiming to upstream their new phone's drivers. Chromebooks typically run a much closer to mainline kernel than Android devices.

https://liliputing.com/fairphone-5-is-a-repairable-e699-smar...

https://lore.kernel.org/linux-pm/20230830-fp5-initial-v1-0-5...