Chicken Thighs with Crunchy Summer Veg

Name: Chicken Thighs with Crunchy Summer Veg
Ingredients: 4 skin-on, bone-in chicken thighs (about 1 3/4 lb. total); 2 tsp. extra-virgin olive oil; Kosher salt; 2 tsp. mustard seeds; 1 tsp. fennel seeds; 3 small cucumbers (such as Persian or kirby), cut into 1 pieces; 1 watermelon radish or kohlrabi, 1/2 fennel bulb, or 4 piece daikon, very thinly sliced; 1 bunch red radishes, trimmed, very thinly sliced; 1 bunch scallions, sliced 1/2 thick; 3 Tbsp. (or more) red wine vinegar; Lightly crushed salted pita chips (for serving)