It seems that there will be a new "color control points" feature in the next update of the free Nikon Capture NX-D photo editing software:
RAW file processing software with color control points — Capture NX-D (free download)
Nikon’s Capture NX-D software is the best way to process original RAW (NEF/NRW) files without losing any of their extremely rich data. You can adjust options such as exposure compensation, white balance, Picture Control, Active D-Lighting and noise reduction using a slider. It also incorporates color control points that let you edit the hue, brightness, saturation, contrast, etc. of a selected area. JPEG and TIFF files are also compatible.
Found on page 53 of the Nikon Z brochure.