GrapheneOS [Unofficial]

Pixel 8 and Pixel 8 Pro are confirmed to have at least 7 years of full support:

https://support.google.com/nexus/answer/4457705?hl=en#zippy=%2Cpixel-later-including-fold

We expect 6th and 7th generation Pixels will also receive major OS updates until the end of their security support period. Bear in mind these are a minimum, not when it ends.

Android only has a single active stable branch, which is the latest major OS release. For example, Android 14 has now replaced Android 13.

Android 11, 12 and now 13 only have standalone backports of Critical/High severity patches and a subset of Moderate/Low severity patches

The alternative to updating 6th and 7th generation Pixels to the latest major OS release until their end-of-life would be continuing to develop an older major release and continuing to have releases for it. We think it's much more likely they give them 5 years of major updates.

It's likely they've already come to that conclusion and it's why it makes sense for the Pixel 8 and Pixel 8 Pro to have at least 7 years of major OS updates to go along with a minimum of 7 years of security patches. It's easier rather than harder for them to do both, especially with Treble.