Interior Cubemap with Dual Depth Relief Mapping.
One of the problems with interior cubemapping is that you are limited to the 6 planes of a box, with the use of relief mapping you could have a fake 3D model in your cubemap but it will have a lot of artifacts if you look at it from an angle. Dual depth relief mapping will fix some if those artifacts.
First thing i saw it in is the UE5 matrix demo:
https://www.youtube.com/watch?v=1vQc4OS9n-I