alt Hacker NewsNot sure where you're getting this from, but the latest MacOS works on devices from 2019 so it's at least 6 years of support. And homebrew supports versions from macOS 14 fully (and some support up to 10.15) which means full support for 2018 devices and potentially even devices from 2012 will work.
Sources:
Well, Tahoe doesn't work on 2019 iMacs, and that chart shows the early 2020 Macbook Air isn't eligible either, so support duration varies a bit.