Perhaps they have not been answered because no one knows the answer.
People have been trying for years to do that successfully. For some reason, doing watercolor in 3d is very difficult.
Have you seen this
Or this: Scroll down to the mention of MixBox being used in Blenders Flip Fluids…
A watercolor material:
A free Oil paint Material for blender:
# Oil Painting Shading in Blender
Have you looked at Blenders Grease Pencil? Some of the new GP Material updates are amazing. Like this video from 4:00 minutes onward.
A 3 day old video from NENGHUO about a Geometry Node Brush…
It would be better to add a new comment to old posts. Then people will see the whole history of what you have tried. Or not tried. What have you learned in the last month? Add your progress to a post so people become interested. When you re-comment, your old post will go back to the top of the new post list.
Good luck…