[maven29]

https://www.engadget.com/samsung-pledges-seven-years-of-upda...

Samsung offers 7 years of major version upgrades on their flagship lineup starting with the S24. It is not retraoctive, although their 5 year policy has been in place for 2021 devices.

It's unlikely that they will offer security patches beyond that point and the mid-range segment still only gets 4/5 years.

Chinese OEMs offer "major" upgrades for longer, however they achieve this by backporting both Android mainline and proprietary features to older versions of Android, along with security patches.