While I think this is a good idea. I have a similar idea that I think would be able to achieve this, as well as be more flexible.
I think colored “groups” in obsidian should have an extra setting that allows their color to bleed over onto connected notes. That way you could tag your “center note” with it’s own unique group and you could see how close everything else is. But you could also do this with multiple notes and see how they connect and overlap.