I heard somewhere that the heterozygous flower's pigment granules are red under the microscope. Either the pigment granules are fewer in number or smaller or there is some other explanation for the pink color. But all my sources accept the nonfunction of the white gene as common knowledge.

I don't understand the statement about the normal gene not having an effect. The normal gene is for red, and it definitely has an effect. It's just that two red genes have a greater effect than one red gene has.

I think of codominance as being like a black coffee and white milk producing a brown colored mix. Both contribute to the final product's color. Incomplete dominance is more like black coffee and water. They also produce a brown colored mix. But only the coffee contributes color. The water just dilutes that color. If the white flower color gene produced a product, then the pink color would be the result of codominance, not incomplete dominance.

Does a breeder really care whether a blended phenotype in a heterozygous snake comes from two different genes with functional products or from two different genes, only one of which has a functional product?