Shader ONLY to 2D Objects

Hello people. Without delay, I go straight to the point.

I use the Bettle PSX HW core, VULKAN renderer and the internal resolution at 8x. I would like to apply the NNEDI3 shader ONLY to 2D objects. How should I proceed?

In FFIX, for example, the models look great at 8x, but the menus and 2D images are out of focus. With 1x internal resolution, everything looks great with NNEDI3, except for 3D models.

Please do not answer that it is impossible. There must be a way to create a shader that recognizes that the internal resolution has been increased and then we can apply our favorite shader to games.

Big hug.