Google has confirmed that its five years of software support for the Pixel 6 series does not cover all software for the devices. Unfortunately, Google can only guarantee five years of security patch updates, with three major OS updates coming the way of the Pixel 6 and Pixel 6 Pro too.
https://www.notebookcheck.net/Google-s-five-years-of-software-support-for-the-Pixel-6-and-Pixel-6-has-a-relatively-large-caveat.574832.0.html
To be honest the newer Android versions don't bring any killer features for me. If anything, Android 12's changes have been a nuisance (reminds me of old Youtube redesigns).
The security updates mean that I can comfortably pass the phone on to someone else without them bothering me about malware. I'd probably worry about the phone battery dying before the updates even stop.