I do have one, but she's mine. I can try hunting for another one though, been meaning to go on another hunt again anyway. Maybe I'll even ask Lav if he wants to join in.
As for the Sprigatito, nope, don't have one, and the shiny for it is just a change in its eye color, so not worth it for me to try egg hunting for such a small change.
If you want to egg hunt it yourself though, I can try to get you a foreign Ditto for breeding, and when you finish your Dex, the Shiny Charm you'll get will help with that as well.
And yes, there are sandwiches that help with shiny hunting, but only for overworld shinies, not eggs.
The best sandwich you can use for eggs is the 'Great Peanut Butter' sandwich, because it gives you 'Egg Power 2' which makes you get eggs faster and makes them hatch faster as well.