Does Sparkling Power work with eggs?

Question

Could make shiny hunting a lot easier, especially with masuda method if it's possible

Answer 1

No.

Sparkling Power only works on wild encounters. Using a Sparkling Power sandwich does not affect the odds of finding a shiny Pokemon while breeding, static encounters (found throughout the map, includes Tera Raids), gift Pokemon, whatever else I can't think of right now.

Source: Experience, but also double checking a couple Bulbapedia articles just to be sure.