If I buy a pixel 6 today, I'll get updates for 2 years.

On apple, iOS 15.2 is available for a phone that is 8 years old?

Based on past experience, I expect if I bought an iOS device today - I'd have updated for at least 5 years.

Apple was releasing updates for iOS 12 as recently as 2021. That's for phone back from 2013 (!).