Both the piano roll and VariAudio enables the option to colors notes by pitch like so:
I would like to have the option to color the notes not by absolute pitch but by scale degree (so first degree is always the same color, regardless of scale)
The scales can be derived from the chord track.
Basically it only matters what the tonic is - other pitches can be colored chromatically from the tonic. The import thing is that first degree (Do) will always have the same color, 2 semitones above the tonic (Re) will always have the same color etc.
I think that’s good because scale degrees are a very musical and intuitive way to conceptualize notes and is often used as a good teaching device for ear training. This way it’s going to be easy to understand what the part will sound like just by looking at it.