What can I do to a normal map to convert it into the pixel normal?

Suppose I have a material where I plug a normal map texture sample into the normal and use Pixel Normal WS. How would I achieve the Pixel Normal WS without using the said node, using only the normal map sample and other nodes like Vertex Normal WS? I tried adding Normal with the Vertex Normal to see if that worked and even normalized it but that doesn’t replicate it.