@pornel of ImageOptim/PNGQuant fame just released a first version of gifski (website, github). Quoting the website,

Highest-quality GIF encoder based on pngquant.

gifski converts video frames to GIF animations using pngquant's fancy features for efficient cross-frame palettes and temporal dithering. It produces animated GIFs that use thousands of colors per frame.

It's a CLI tool, but it can also be compiled as library for seamelss use in other apps (note that for closed-source apps you need a commercial pngquant license).

Would be awesome for Peek to be able to directly use it. Probably as an option (?) as I guess it means good-looking but heavy GIFs, which depending on the use case may not be the user-desired tradeoff.