Don’t forget to vote for this feature if you want it to be added! 
Someone recently pointed out that Silver Efex Pro in the Nik Collection has a luminance zone tool (see here). Can you explain a bit more what the usefulness of displaying luminance zones in PhotoLab would be? I can imagine one or two uses, but anything you can say about why we need this feature would help increase the vote count and ultimately convince DxO to implement it in a future release.