Cell-shading in Cycles

Many times people have asked for "Shader to RGB" to be added to cycles, and that has rightfully been declined, because cycles and eevee is fundamentally different.

But, the main reason one would want that feature in the first place. Is to be able to put it through a color-ramp, and choose the colors that are displayed, so you can achieve a cell-shading look. So forgetting about the shader-to-rgb node entirely.

If a cycles node could be created, which enabled the effect like the shown eevee node setup below.

The input would be 2 colors, or shaders. And sliders enabling to change the harshness of the shadows. Other ideas to achieve control are welcome!

Now why would anyone wanna do cell-shading within Cycles? Isn't Eevee enough? In some cases, yes, but in many others you want to mix and match effects, and are very limited by the game-like grapics eevee provides. I think more tools for artistic expression and toon like effects like this in cycles would benefit everyone