In G'MIC, there is a preset (under Art subdirectory) called Shapism. The problem with that preset is it usually yields unfocused results. I use another G'MIC preset called b/w dither and feed that into Shapism instead (using transparent background color instead of the default black). Create a mask by chosing Alpha to Selection and highlighting the GIMP toggle selection option, I copy that and then untoggle and selection none. I then paste for the mask. I then run Threashold (moving slider left to brighten) for the mask and run Blend (Shape Average) with original image (Blend (Shape Average) is located in Testing folder>Lylejk; David saved this preset for me when he went another direction with the preset; I like the original behavior better, and definitely appreciate that David saved this preset under the Testing section). I then add layer mask and past the mask in that to smooth out the dots. Maybe the programmer gurus here can automate this flow. I do use a copy of the threshold mask and apply a convolution layered dot set to grain merge to push more details, but that's part of the secret sauce I use. lol
Create the convoluton layer by duplicating the original, and on the base layer I run Sharpen (Gradient) and set the top layer to Grain extract and merge down. I then used Blend (Shape Average) on the convolution layer with the threshold mask as mentioned to convert it to dots which I then set to Grain Merge over the colored dot result. This step, again, adds more perceived contrast/details to the dots as a whole (globally that is).