There has not been a lot of attention to the quality of the videos from the GoPro Fusion in low light. In fact, my experience is that its low-light ability is greater than the Hero7 Black, the Osmo Pocket and the Sony RX0. This is in line with theory. Why?
The size of the sensors in the Fusion are the same as that in the Hero7 Black and the Osmo Pocket. But, the number of pixels is less, so the pixels are bigger and absorb more light (9 megapixels versus 12 megapixels in the same area). Moreover, the lenses on the Fusion are f2.0, that on the Hero7 Black is f2.8. Thus each Fusion lens lets in twice
the light as the lens on the GoPro. The lens on the Sony RX0 is f4.0; it lets in 1/4th
the light of the Fusion. And the Sony's larger sensor, packed with pixels (20), does not make up for the loss of light. I think the Fusion's low-light ability may also be better than that from the Sony RX100 VI, with its f2.8 lens at the wide end.
My goto place for dim light is Grand Central Terminal. So, here is a 5.6K Fusion 360 video from there:
Again, for seeing maximum quality, choose 5K from the gear. You can download the original stitched Cineform 5.6K video from here: