[wmf]

Did you try -q 100? That might be an idiom for lossless.

[rorrr]

I did, and it produced a huge .webp file, 6.7 times larger than the original PNG.

[salmanapk]

rtfm? Check the examples at the bottom: https://developers.google.com/speed/webp/docs/cwebp

[rorrr]

Did you read that link yourself?

The word "lossless" isn't even on that page. I tried setting the highest quality, but that just produces huge files.