I want to use the light probe as a fisheye or spherical camera in Eevee. How can I directly access image data produced by the lightprobe? I want to use the light probe as a fisheye or spherical camera in Eevee. I assume a panoramic fisheye option will be developed for Eevee at some point, but in the meantime perhaps the light probe can meet my needs.

I made a pretty hacky rig, in which light probe-driven reflections are used on a sphere. A camera points at the sphere and produces a passable fisheye, but this isn't a very elegant solution and you lose some information, like alpha.

Ideally, I'd like to have a composite node or image-type object that provides access to the data. I don't mind Pythoning my way to it though if I can get pointed in the right direction. The bottom line is if I can get whatever image the light probe is producing, I can work with that to get what I need.
The light probe/reflection cubemap is created with 6 image planes in a specialised image format like DDS. It's not spherical.

It is however possible to convert a cross image (composed of 6 renders from each axis into a cross) to a longitude/latitude image using CMFTStudio or Knald Lys.