If you wanted better compression, it's called Lossless WEBP. Lossless WEBP is such a nice codec. Compared with Lossless JXL, it decompresses many times more quickly, and while JXL usually produces a smaller file, it doesn't always.
Lossless AVIF is not competitive.
However, lossless WEBP does not support indexed color images. If you need palettes, you're stuck with PNG for now.
replies(4):