Place the eggs in a saucepan and add enough water to cover them. Bring the water to a boil over medium heat. Once the water reaches a rolling boil, reduce the heat slightly and let the eggs cook for 9-12 minutes.
While the eggs are cooking, prepare a large bowl with ice cubes and water. This will be used to cool the eggs and stop the cooking process.
After the eggs are cooked, carefully transfer them to the prepared bowl with ice cubes and water. Let them sit for about 5 minutes to cool completely.
Once the eggs are cooled, gently peel off the shell.
Cut the hard-boiled eggs in half lengthwise. Carefully remove the yolks and place them in a bowl.
Mash the egg yolks with a fork until they are crumbled and add the mayonnaise, Greek yogurt, Dijon mustard, onion powder, salt, and pepper to the bowl with the mashed yolks. Mix well until smooth and creamy.
Add a small amount of orange food gel colorant to the yolk mixture and stir until the desired pumpkin color is achieved. Adjust the intensity of the color by adding more gel if needed.
Spoon or pipe the yolk mixture back into the egg white halves, creating a rounded shape resembling a pumpkin.
Place the sliced scallions on top of each deviled egg to create the "pumpkin stem."
Serve chilled as a festive and keto-friendly appetizer or snack.