As the title says… there appears to be no way at all to modify the UV of the _CameraOpaqueTexture, even though numerous tutorials I’ve read online show doing just that to get some nice distortion. As the attached image shows, I’m creating a sprite shader with distortion, and I’ve gotten it to the point where it renders out the _CameraOpaqueTexture just fine, and I can modify the output of the SampleTexture2D node just fine. But nothing I do affects the UVs, which is what I kind of need to be able to distort it!
With Scriptable Render Pipeline, you can toggle a setting that causes _CameraOpaqueTexture to give you the render output from the camera (described here for reference: Fabio R. Colombini: ShaderGraph - Refraction).
In the above example I am showing that even without a texture, the material does not warp the shader. This same problem occurs regardless of what shader type is used.
My final end-result is do essentially have things like glass and water that warps what is behind them.