The Qt6 CMake files do not create CMake targets for their plugins. For instance, Qt6Gui is missing targets for its plugins & platform modules, but this appears to apply to all modules that have plugins (eg, also Qt3D).
Qt6GuiConfig.cmake has the following check:
However, the file it is looking for does not exist, and hence no plugin targets appear to be getting loaded at all. This is breaking my build/install logic.