Lessons learned:

The key was randomness. The photo wasn't ideal in terms of lighting setup for painting. I threw random gradient maps at it and tweaked colours to flip the light and dark areas.

This helped some but still looked a bit odd. I added a threshold underneath the gradient map and it added strong lines of black and white. The gradient on top smoothed it out a little and added colour but the effect of the strong delineations was there. That made it very easy to paint details and have proper detail in the strokes.

Then added LUTs on top

I also checked the hue randomisation setting in the brush dynamics panel. That introduced random hues which lead to more of a painterly feel