Since Android 4.2, Google has supported partial (not fully 360x180) equirectangular photos via the publically documented Photosphere format - https://developers.google.com/streetview/spherical-metadata
Skybox claims to support "all video formats" - but what about stills? Google's photosphere XMP has been around since 2012, with support for tagging it in panorama stitching applications like Hugin since at least 2014-2015 - so why is it that Skybox chokes on Photospheres with proper XMP metadata? Having to post images to Facebook Photos (and suffer the inevitable loss of image quality as a result) is incredibly frustrating.
It's possible to work around this by padding up a Photosphere to 360x180 with black pixels, but this frequently leads to Skybox crashing due to the texture being too large. (At least Google Camera's Photosphere feature had an effective limit on image resolution as a whole, not resolution per degree, so partial Photospheres were of higher resolution than full 360x180 ones.) Yet Android phones and tablets far less capable than the Snapdragon 821 present in the Oculus Go have no issue with the same images.