I've used small dots, and a few large dots, of just a few colors, and black and white, in different combinations, to, hopefully, fool your eyes into seeing many color variations. Why? Because that's the point of pointillism.
The six colors on the left, plus the black and grey*, are as close as I could get to the basic ink colors Spoonflower uses for printing (my program won't allow decimals in LAB). There is one complete set of color combinations on a FQ, plus an additional row of the solid colors on the right
*Note: the grey in the shadow is at full saturation and the background dots are simply less saturated.