How can I get screen space normals in a material?

If you want vertex normals in screen space, place down “Vertex Normal” node and then a transform node (not transform position, just transform) with the source set to WorldSpace and the destination set to ViewSpace. Then go to the material properties and uncheck “Tangent Space Normal”. You may need to flip the normals by multiplying by -1 depending on what you are trying to do.

For pixel normal just replace “VertexNormalWS” with “PixelNormalWS”.