Scientific Field Visualizations in Unity

What would be the best approach to do a visualization of a 3D electric field in unity like what is done on

https://www.falstad.com/wavebox/
This was done in WebGL I think. It looks like tiny glowing pixels changing color and moving in 3D.

Would I just use a gpu mesh instancing with some sort of shader for a glowing sphere?
The shaders or materials I've tried so far just look like little spheres not like glowing pixels.
If I cover a 100x100x100 box with gpu instances that would be 1,000,000 of them and I'm not sure
if the computer can handle that.

What's the best way to duplicate this type of visualization?

 

Looks like raymarching through a 3d texture.