So I generated this pie shape and I was wondering if I could save it to a texture in UE4? I would like to load it up into a TextureSample node for further processing.
This is very simple, you just need to render your material to a RenderTarget in a Blueprint and then create a static texture from it(right click on the asset in the content Browser). Just make sure you use the emissive output in your material.
In this Video from Epic, they explain how it is done in more detail.