You're absolutely right! This seems very trivial to add. I just did a quick test and added a "PicoCAD" option to the dither patterns that goes perfectly with the PICO-8 palette that PixDither already has! To keep this plugin backwards-compatible, I had to add it wayyy at the end of the list though:
I went ahead and uploaded a new Windows build with this one added! Lemme know how it goes!
There will be some delay getting an updated OSX build uploaded due to my current build pipeline being kind of cheesy.