No, you really shouldn't use real nail polish
It's pretty bad for resin.
My process for mani/pedis is to seal the doll, blush the nails with pastels to define the edges of the nail (and the moons, if you want), seal again, paint the edge with very small brush with white acrylic, seal and gloss. If you're doing a solid color to look like nail polish, it's a lot simpler. Seal, blush the hands, seal, paint the nails, seal and gloss