OK I think I found the winner, this is the pipeline:
blur 0x1
quantize as YIQ/YUV
convert down to 32 colors with dither
scale down by 1/8
sharpen 3x3
scale back up to original size
the imagemagick command I used for this was:
magick input.jpg -blur 0x1 -quantize YIQ +dither -colors 32 -filter point -resize 12.5% -sharpen 3x3 -resize 800% output.png

















