Can't display raster or GL in 10-bit color depth on most platforms

I'm trying to paint 16-bit QImage using QPainter in Qt application using 10-bit deep color monitor, here are my results:

• Linux/X11 with `DefaultDepth 30` Xorg config - Works (color banding almost not visible)
• Linux/Wayland - Doesn't work (color banding visible)
• Windows - Doesn't work (color banding visible)
• macOS - Doesn't work (color banding visible)

Any platform:

• QPainter + QtWidgets OpenGL composition enabled with `GL_RGB10_A2` texture format - Doesn't work (color banding visible) when painted on different widget, works when painted directly on QOpenGLWidget only on Linux/X11 with `DefaultDepth 30` Xorg config
• Vulkan application using native Vulkan API calls - Works (color banding almost not visible) - it means my monitor / system config is working correctly

Is it any chance to improve 10-bit deep color in Qt for non-X11 platforms and/or QPainter with OpenGL widgets compositing?