Heat the oven to 350°F. Line a rimmed baking sheet with parchment paper.
Cook 4 slices bacon in a medium skillet over medium heat until crisp, 4 to 5 minutes per side. Using tongs, transfer the bacon to a paper towel-lined plate.
Remove all but 2 tablespoons of the bacon fat from the pan. Add ⅓ cup panko breadcrumbs to the pan and cook over medium heat until the breadcrumbs are golden-brown and toasted, 1 to 2 minutes. Transfer to a small bowl.
Finely chop the bacon, then transfer to a medium bowl. Stir in 8 ounces room-temperature cream cheese, 4 ounces shredded sharp cheddar cheese, 2 tablespoons minced fresh chives, the finely grated zest of 1 medium lemon, 2 teaspoons lemon juice, ¼ teaspoon garlic powder, ¼ teaspoon kosher salt, and ¼ teaspoon black pepper until combined.
Arrange 24 jalapeño pepper halves cut-side up on the baking sheet. Divide the filling evenly between each half (heaping 2 teaspoons each). Top evenly with the toasted breadcrumbs.
Bake until the jalapeños are tender and the filling is heated through, 20 to 22 minutes.
