Hard boil the eggs, then let them cool fully. It's even better if you do this the day before.
Peel all the eggs. With two knives, slice the eggs into bits (much in the same way you'd pull pork with two forks). The smaller the better, but don't worry about getting things perfectly even here.
Add the mayonnaise, Greek yogurt, mustard, and celery. Add the pickle relish to taste, pressing excess liquid out of the relish before mixing in.
Add salt and pepper and stir to combine. Taste and adjust as needed!
Serve over a bed of lettuce, on a sandwich, or inside a wrap.