You generally have difficulty actually running contemporary build tools on such a thing, so the workaround is to use —-sysroot against what is basically a chroot of the old distro, as if cross-compiling. But there are still workarounds needed if the version is old enough. Chrome has a shorter support window than some Linux binaries, but you can see the gymnastics they do to create their sysroot in some Python scripts in the chromium repo.
On Windows, you install the latest SDK and pass a target version flag when setting up the compiler environment. That’s it. macOS is similar.
You can see what the best-in-class hoop jumping looks like in a bunch of open source projects that do binary releases — it’s nontrivial. Or you can see all the machinations that Flatpak goes through to get userspace Mesa drivers etc. working on a different glibc version than the base system. On every other major OS, including other free software ones, this isn’t a problem. Like at all. Windows’ infamous MSVC versioning is even mostly a non-issue at this point, and all you had to do before was bundle the right version in your installer. I’ll take a single compiler flag over the Linux mess every day of the week.
Do you distribute a commercial product to a large Linux userbase, without refusing to support anything that isn’t Ubuntu LTS? I’m kind of doubting that, because me and everyone I know who didn’t go with a pure Electron app (which mostly solves this for you with their own build process complexity) has wasted a bunch of time on this issue. Even statically linking with musl has its futziness, and that’s literally impossible for many apps (e.g. anything that touches a GPU). The Linux ecosystem could make a few pretty minor attitude adjustments and improve things with almost no downside, but it won’t. So the year of the Linux desktop remains illusive.
