Unless I missed a memo, Linux LTS is 2 years of support these days. Many distributions offer 10 year LTS releases, but I’m not sure of any off the top of my head that currently offer more.
I feel like a couple things were mixed that aren't the same. The commenter upthread said 10 years for Windows OS versions. I took that to mean e.g. "Windows 11 will be supported for 10 years from initial release".
Sure, you can often install a modern Linux distro on a 20-year-old device (though just as often, you cannot), but that's not the same thing as a single version of Windows being supported for 10 years. The analogous situation is indeed LTS versions of Linux distros, which certainly don't have 10-year support lifetimes, let alone 20.
But the support lifetimes make sense for the various vendors. Apple doesn't need to support a particular major version of macOS or iOS for all that long, because they make sure new versions of their OSes will run on fairly old devices (all of which are devices they've built, and have full control over), and they aggressively push people to upgrade to new major versions as they come out.
Microsoft has a lot of customers who value stability and consistency above all else, and on top of that, they have to support a wide variety of hardware that they don't and can't control. Supporting a major version of Windows for many years makes sense for them.
As for Linux, there's no one single source, so a rolling-release distro can decide to only support the bleeding edge, whereas a cloud provider might roll their own distro for server use and decide to support that for a decade, if they think that's what their customers want.
