This would be somewhat possible via a shader, but unfortunately custom shaders were denied and the chances of roblox making this in general are fairly slim. The only drawback from a post processing effect VS an actual effect in the late render pipeline would be that a post processing effect simply handles the screen as if the displayed contents were a texture (I’m sure you know this), so it can’t actually go in and grab contents from something potentially off-screen via a refracted ray.
But yeah, I could see how that may be a way to go about it.