If you can find any way to get normal map variation into your object’s materials, cubemap refractions will work very well- like @BananableOffense said, most people don’t correctly intuit accurate refraction, just an approximation of the scene around them, which cubemaps nail if there’s even a little bit of obscuring what the refraction origin is. Also, the per-pixel cost is dirt-cheap, so you could have a ton of these at once. I wonder if the custom LUT refraction approach outer wilds used might also be worth considering.