G'MIC Color Masking

Something I had in mind is to be able to manipulate data much in the same way that ac “something something”,rgb , but you can do it by colors instead of channels. What would be the best approach for this? One application is being able to adjust chroma/saturation by either hue_rgb or by mixed lab channel where at least 1-half of the 2 channels are used for something like blue-green or orange.

The CLI command name would be acm (eq. to apply_color_mask)
Description : Apply command on specific colors specifying colorspace model and colors.

Another idea I had in mind is ecm (eq. to extract_color_mask)
Description : Extract by colors.

ColorsColor mask [interactive]. See: Release of G'MIC 2.0.0.

I found select_color and select_replace color. I never knew these things exist though to be fair, with a lot of filters and code, it can be easy to miss.