I would like a "reference layer" feature in the desktop version of Photoshop. Fresco already has it and it works great, but I would also like this feature in the desktop version of Photoshop. Photoshop is my main illustration tool, which I mainly work with every day.
Adobe fresco has a feature where you can change the drawing's line layer to Reference layer. After the change, you can drop colors onto the new layer, but the colors remain behind the line and on their own layer. You can work with lines on their own layer and colors on their own layer.
Fresco - Reference layer - https://helpx.adobe.com/fresco/using/layers.html