Preheat a grill to high heat and oil the grates or preheat oven to 425°F, place a rack in the center of the oven, and line a baking sheet with parchment paper.
In a large bowl, mix wings with garlic powder, onion powder, salt, and pepper. Drizzle with olive oil and toss to combine.
Meanwhile, make the butter sauce. Melt butter in a medium skillet or saucepan over medium heat. Add peperoncinis, peperoncini liquid, and garlic. Mix to combine and cook until fragrant, 2 minutes. Season to taste with salt and pepper. Keep warm.
If grilling the wings, place the wings on the grill grates and cover until all sides are deeply charred and the chicken registers an internal temp of 165°F, 7-8 minutes per side.
If baking the wings, arrange wings on prepared baking sheet and bake until golden brown on all sides and the chicken registers an internal temp of 165°F, 45-55 minutes.
Once the wings are cooked through, add them to a large bowl. Drizzle with butter sauce and toss to combine. Transfer to a serving platter and top with feta and chives. Serve immediately.