Heat oven to 450F. (Skip this step if using air fryer.) Brush potatoes with 2 tsp oil and season with 1/4 tsp salt. If using an air fryer, place in basket and cook on 390F until tender on the inside and crisp on the outside, 30 to 40 minutes (or 45 minutes in the oven). Halve potatoes lengthwise and let cool slightly. While potatoes are cooking, arrange bacon on a rimmed baking sheet and roast, flipping after 10 minutes, until crisp, 15 to 20 minutes total. Transfer to a paper towel-lined plate; break into pieces when cool. Once potatoes are cooked, halve potatoes lengthwise and let cool slightly. Scoop out insides of potatoes, leaving a thin border all the way around (save insides for another use). If desired, pop back in oven and roast until crispier, 6 to 8 minutes. While potatoes are cooling, prepare spinach: Heat 2 tsp oil and garlic in a large non-stick skillet on medium until sizzling. Add spinach, season with 1/4 tsp each salt and pepper and cook, tossing until just wilted, 2 to 3 minutes; transfer to a bowl. Wipe out skillet, add 2 tsp oil and return to medium-low heat. Beat eggs with 1 tbsp water and a pinch of salt and scramble to desired doneness. Brush insides of potatoes with ghee, top with eggs, spinach and bacon. Sprinkle with parsley and dollop with pesto, if desired.