I think my idea is interesting. Could we render directly to a vector format in Blender 3D? If this is possible and gives good results then you could scale up the image without much pixel errors. Which is good for photo prints. I don’t mean that you should render the image with pixels and then convert it. Rather Blender should somehow generate a vector image directly. A guess would be a system of bitmap layers that combined could easily be converted to a vector image.
Another idea is to print out your rendered images in a photo print shop to paper. If you render at 6 MPixels or more it will look stunning.