I used the Nix colour scanner and got good results: https://www.nixsensor.com.
I brought the head into my local Dulux paint store and they actually used a Nix as well.
I used the RGB mode and plugged these into the Golden Color Mixer for playfield touchups: https://education.goldenpaints.com/mixer
Not always perfect (I didn't mix by weight so probably my mix was not quite correct) but gets you 98% of the way there.