In my experience, not really. For me, when WMR plugin is enabled, VR mode is grayed out (disabled). VR preview still works. With the plugin disabled, you get Vive motion controllers and VR mode works. By native support perhaps they mean all the input streams handled - tracking and accessing motion controller input events works fine because the brilliant engineers made these functions generic to all HMD systems.
Note I just got the WMR headset and am still a novice. So perhaps there are check boxes or settings or configurations I’ve missed that would allow WMR to work in VR editor mode.
I know I want this feature!