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 (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.

https://grapheneos.social/@GrapheneOS/111177489013595659