Fry the pancetta in a large skillet over medium heat, until all pieces of pancetta are crispy on the edges, and most of the fat on the pancetta has been cooked away. Remove the pancetta from the skillet onto a plate covered with two layers of paper towels; set aside to drain.
Halve the hard-cooked eggs lengthwise, and place the yolks into a prep bowl. Add all of the remaining ingredients (mayonnaise, vinegar, pepper, sugar, celery seed, chives) to the bowl, except for the pancetta. Stir well and mashing the mixture until creamy.
Once the pancetta/bacon has drained and cooled, cut it up into very small pieces. Reserve two teaspoons of the pancetta for garnishing the finished eggs, and add the remaining pancetta to the yolk mixture.
Spoon or pipe the egg mixture into egg white cavities. Garnish with some fresh chives and the reserved pancetta pieces. If not serving immediately, cover and refrigerate.