Preheat your oven to 400°F (200°C) and line a small baking sheet with parchment paper.
Dice the potato into 1/2-inch cubes and toss them in a bowl with the olive oil, sea salt, black pepper, and garlic powder.
Spread the potatoes in a single layer on the baking sheet and roast for 20-25 minutes, flipping halfway through, until they are golden and crispy.
While the potatoes roast, whisk together the whole eggs, egg whites, and dried oregano in a medium bowl.
Heat a non-stick skillet over medium heat and add the baby spinach, sautéing for 1 minute until just wilted.
Pour the egg mixture into the skillet over the spinach and let it sit for 30 seconds to begin setting.
Using a silicone spatula, gently push the eggs from the edges toward the center to create soft curds.
When the eggs are nearly cooked through but still slightly moist, sprinkle the crumbled feta cheese over the top.
Fold the cheese into the eggs for another 30 seconds until the eggs are fully set.
Plate the fluffy scrambled eggs immediately alongside the hot roasted potatoes.