I never finished it, but during a hackathon I did try and make a codec around FLIF (which more or less merged with/morphed into JPEG XL IIRC). I didn't get too

I never finished it, but during a hackathon I did try and make a codec around FLIF (which more or less merged with/morphed into JPEG XL IIRC). I didn't get too far, but it was one of those things that I didn't really understand why no one else had done it. So I think a codec based around JPEG-XL sounds cool. Someone should do it.