There's no QT vs GTK situation on Mac. Windows has more of a mix of UI, but at least compatibility tends to be preserved.
Besides that, macOS and Windows each only have one DE and one window system. So in tutorials or IT help, it's enough info to specify that you're using "Mac" or maybe "Mac Tahoe," not "Linux, Debian Trixie, KDE Plasma, on Wayland." Not to mention hardware-specific issues, though those aren't Linux's fault.