ffmpeg png optimization like libpngquant?
I'm not aware of anyone working on this.

Is this the library you're referring to - https://pngquant.org/lib/?

This appears to generate a palette and then perform the usual PNG encoding upon the palettized image. If so, this can already be reproduced in FFmpeg.

ffmpeg -i image -filter_complex palettegen[pal];[0][pal]paletteuse,format=pal8 out.png


See docs for paletteuse for dithering options.



If the specific algorithm were to be added to FFmpeg, it would be as a libav filter, not as changes to the PNG encoder. Although given existing functionality, most acceptable way forward is to improve the palettegen/use filters if their quality isn't acceptable.