Combine jerk seasoning, olive oil, salt, black pepper, and lime juice in a mixing bowl to create the marinade.

Coat the chicken thighs with the marinade and let them marinate for at least 30 minutes to 2 hours.

In a saucepan, combine apple cider vinegar, sugar, a pinch of salt, ground ginger, and optional red pepper flakes over medium heat. Stir until sugar dissolves.

Remove from heat and stir in diced pineapple. Cool and refrigerate for at least 30 minutes.

Preheat grill or skillet on medium-high heat for 5-7 minutes.

Cook marinated chicken thighs skin side down for 6-7 minutes, then flip and lower heat, cooking for an additional 15-20 minutes until internal temperature reaches 165°F.

Let the chicken rest for 5 minutes before serving topped with pickled pineapple.