I Don't Need Tangent Space Normals

Unity Standard Surface Shader uses "Tangent Space Normals" but I'm creating a custom bump solution that doesn't need tangents and I want to remove the configuration from the Standard Shader if possible.

My bump solution uses custom bump maps and works perfectly when applied in an Unlit Shader using "Normal Space Normals".

Is there a way to simply get the Surface Shader to use "Normal Space Normals" without losing the other features like Tessellation?