The Nikon Keymission 360 features electronic image stabilization (called electronic Vibration Reduction). The Keymission 360 uses a built-in gyroscope to record its horizontal, vertical and rotational movement. Using the information, vibrations are offset during playback for a smoother-looking video.
As described, the image stabilization appears to be different from vertical orientation correction (which cannot correct for horizontal or vertical movement).
Note: Nikon's image stabilization doesn't work at the full 4k resolution. It works only at 1920 x 960 resolution.
I took a couple of test videos to test whether the Keymission's image stabilization works, one without stabilization, and one with stabilization:
To me, I think the effect of the image stabilization in this sample seems minor. What do you think?