I want to use a HiDPI screen and a "LoDPI" screen together. Why can't I do that on Linux (X11), barring Wayland which seems to crash pretty constantly? How will

I want to use a HiDPI screen and a "LoDPI" screen together. Why can't I do that on Linux (X11), barring Wayland which seems to crash pretty constantly? How will a Linux laptop help here?