Thanks to some help from Evgeni_Popov here are two PGs based on @jerome’s suggestion. Both have 1 million points, the first uses the CPU, the second a shader. You can see the difference
CPU - https://www.babylonjs-playground.com/#U2C1Q6#6
Shader - https://www.babylonjs-playground.com/#U2C1Q6#5
Of course @Deltakosh’s change to GPU particles gives a more straightforward approach.