Cook and stir bacon and red onion together in a skillet over medium heat until bacon is crisp, about 10 minutes. Remove skillet from heat and transfer bacon and onion to a plate, reserving drippings in the skillet.
Stir salt, black pepper, paprika, garlic powder, cumin, rosemary, thyme, and celery seed into bacon drippings. Roll potatoes into seasoned bacon drippings until evenly coated.
Preheat grill for medium heat and lightly oil the grate.
Cook potatoes on grill until golden brown and tender, about 10 to 15 minutes per side. Cool potatoes slightly; cut into bite-size pieces.
Mix pickles, pickle juice, mayonnaise, and Dijon mustard together in a bowl until smooth. Stir bacon, onion, and potatoes into mayonnaise mixture until evenly coated.