There are Qt analogs for just this thing (QStandardPaths, https://doc.qt.io/qt-6/qstandardpaths.html) to drastically simplify what can be a quite annoying task if you're trying to write GUI software that respects the OS standard file locations across multiple desktops.

This is a different problem than migrating file locations in the same OS, as what the linked blog post is about, but it is a related issue for apps intending to be multi-platform.