If you want to run a phone effectively forever, I am afraid that you need to turn to the free software community, and give up a lot in terms of app compatibility and the many other benefits of living within a mainstream ecosystem. Going the Free Software route is not easy in my experience.

The good news is, one of the great benefits of Pixel phones has always been that the boot loader is unlocked. So, realistically, you can run your phone as long as you want. There are many Free options to keep that going, if that is truly what you value.