I'm thinking that found a fast enough way to do it.
Video:
https://www.dropbox.com/s/yl9eid27jh1z0 … 4.mp4?dl=0

Example attached.

You ask about the Online Maps, right?

Actually, this is a very interesting question.
I've never tried to do so.

10k markers on the map at the same time, will work quite slowly.
In this forum you can find an example of a million markers, but it uses tricks to reduce the number of simultaneous markers on the map.

If do not use markers (because they have a lot of logic that you do not need), and directly position GameObjects on the map, or generate meshes, I think it is possible.
The main question is: you can to write highly optimized code that will calculate as many points?!

Tomorrow I'll try to do it, and, if possible, to give you some example.