I made something like this around 10 years ago to show wireless frequency coverage, luckily the country I was living in is small enough and close to the equator, I didn't support the curvature of the earth so I can't start to imagine how difficult it must have been to visualize it in the browser https://sourceforge.net/projects/waire/ in my case the earth was kinda flat lol, it was fun parsing the map data available back then and playing with SVGs, back then the rendering engine from Opera browser was unmatched