im interested in this subject too,
i use to work with opencv and its warping methods
my guesses are
method1 : we should try to use UV coordinates to modify the texture appearence in the material
method2 : try to modify the texture itself on the material
I dont know if method 1 would work but i’ve seen how people use random UV images to what players see using post process so my guess
is it could somehow modify the rendering of pixels of the texture.
For method 2 i think it requires a bunch of coding , some months ago i worked with a kinect plugin wich was generating a new texture on each update to show the RGB camera as a material so i know that creating a new texture for each render tick is posible, the missing part would be to get the texture send it to a custom function (there is a special node in the material graph) warp the texture and return the new texture.
i will keep reading on the subject i would prefer to use native functions of the engine but as you mention i could not find any of them to change textures.