This sounds very cool, I never knew this. Could you give me an example of such pack?
This one is particularly interesting because it integrates block data in the rendered world along with some server-side augmented data to render a minimap in a vanilla client: https://github.com/JNNGL/VanillaMinimaps
This one is particularly interesting because it integrates block data in the rendered world along with some server-side augmented data to render a minimap in a vanilla client: https://github.com/JNNGL/VanillaMinimaps