In a mixing bowl, combine the jerk seasoning, olive oil, salt, black pepper, and lime juice. Mix well.
Add the chicken thighs to the bowl and thoroughly coat them with the jerk spice mixture. Cover with plastic wrap and marinate in the refrigerator for at least 30 minutes, or up to 2 hours for more flavor.
In a saucepan, combine apple cider vinegar, sugar, salt, red pepper flakes (if using), and ground ginger. Heat over medium heat until the sugar dissolves.
Remove the saucepan from heat and stir in the diced pineapple. Allow the mixture to cool, then transfer to an airtight container and refrigerate for at least 30 minutes.
Preheat your grill or skillet over medium-high heat. Add the marinated chicken thighs, skin side down, and cook for about 6-7 minutes until the skin is crispy and browned.
Flip the chicken thighs and continue to cook for another 15-20 minutes or until the internal temperature reaches 165°F (75°C).
Once cooked, remove the chicken from the heat and let it rest for 5 minutes.
Serve the jerk-spiced chicken thighs topped with pickled pineapple.