Astute Graphics has an Illustrator extension "Stipplism" . It obviously can convert greyshades to dot densities + more. I haven't it, but check it here https://astutegraphics.com/software/stipplism/
A radial gradient can be the first objects to get it.
If you do not want Stipplism and the blending approach isn't good, then you can trace a bitmap, which has the effect.
The bitmap is easily copyable from GIMP. There you make a radial gradient and dither it to 1 bit indexed mode.
At first make an empty image, have quite low pixel dimensions to keep Illustrator load reasonable. Here is a 200 x 200 pixels RGB image and a radial gradient is just under construction:
There's a circular selection to keep the edges empty. The gradient isn't fully linear. There's a middle stop to make the sparse center wider. The shade range is only about 60%...100% white, because darker greys will make contiguous blocks in the dithering process.
Image mode is converted from RGB to Indexed (it's in the Image menu). Here's the dialog
I converted it back to RGB, but it seems to work in Illustrator as well when it's copied and pasted as is. Here's the tracing dialog:
Note: the accuracy is stretched to maximum in the tracing settings and white is ignored.
The result contains nearly square dots. If you want round ones, do the following:
- expand the live trace to make the result editable
- with Path > Simplify transform all curves to straight lines
- apply filter Stylize > Round corners; you must measure one dot in high zoom to see the proper radius if you want to be careful. Fortunately too big radius doesn't harm.
- make the result editable with Object > Expand Appearance
Here's a zoomed picture of the final result: