Combine ground chicken, salt, pepper, maple syrup, Dijon mustard, garlic powder, and paprika in a bowl; mix gently until just combined.
Shape into four ¾-inch patties, pressing a small indent in the center of each.
Heat a grill or skillet over medium heat, lightly oil, and cook patties 5–6 minutes per side until golden and the internal temperature reaches 165°F (74°C).
In the last minute, top with Swiss cheese, cover, and let it melt. Toast pretzel buns until lightly crisp.
Assemble with patty, sauerkraut, and crispy onions; drizzle with extra maple syrup or Dijon mustard and serve warm.