I have made volumetric lighting using Billboard GUI.that have Image Labels with translucent gradient circle.
Here’s the place ID if you’d like to mess around with it yourself.
A really nice aspect is that it can run decently smooth without any optimisation.
It’s done by putting a lot of Billboards with 0.99 image transparency in a cone pattern.
The light beam shining through the Billboards illuminate them where the light actually is,sort of amplifying it.
But as expected,it is still visible at large enough distances.
And even worse,putting your camera on the edge where it’s visible will turn most things grey.
If you’d like to take it upon yourself to fix both Optimisation and Visibility problems then feel free to!