Cut the chicken into 1-inch strips and set aside on a cutting board. Dice the onion into thick slices, and cut both the red and green peppers into 1-inch strips (keeping them chunky so they don't overcook). Mince the jalapeno finely. Drain the pineapple chunks, reserving about 1/4 cup of the juice. In a small bowl, combine the chili powder, cumin, garlic powder, salt, and smoked paprika—I like to mix these spices together first so they distribute evenly throughout the chicken rather than clumping up.
Heat 2.5 tbsp of coconut oil in a large bowl over medium heat for about 30 seconds until it's just warm and slightly liquid (this helps the spices distribute better). Add the spice mixture from Step 1 to the warm oil and stir well to create a paste-like coating. Add the chicken strips and toss thoroughly, making sure every piece is well coated with the spiced oil. Let this sit for 2-3 minutes so the chicken can start absorbing the flavors.
Preheat your oven to 425°F. While it heats, spread the spiced chicken from Step 2 onto a large rimmed baking sheet or two smaller ones, arranging it in a single layer. Scatter the onion, peppers, and minced jalapeno over and around the chicken. Distribute the drained pineapple chunks evenly across the pan, then drizzle everything with the honey and lime juice. I find that spreading everything out properly ensures even cooking and good caramelization on the vegetables.
Place the prepared baking sheet(s) in the preheated 425°F oven and roast for 10 minutes. After 10 minutes, carefully pull out the pan(s) and give everything a good stir, rotating the pan if using just one, to ensure even cooking. Return to the oven for another 3-5 minutes until the chicken is nearly cooked through and the peppers begin to soften and show light browning.
Switch your oven to the broil setting and place the pan(s) on the upper rack, about 4-6 inches from the heat source. Broil for 3-5 minutes, watching closely to avoid burning, until the chicken is fully cooked through and the pineapple and vegetables are caramelized and slightly charred at the edges. The high heat will add a nice depth of flavor and finish cooking any thicker chicken pieces. I always keep an eye on this step since broilers vary widely in intensity.
While the fajitas finish under the broiler, warm your corn tortillas. You can place them directly over a gas flame for about 30 seconds per side, wrap them in foil and warm them in the oven at 350°F for a few minutes, or use a dry skillet over medium heat. Transfer the cooked fajita mixture to a serving platter or directly onto plates. Sprinkle the fresh cilantro over everything and serve immediately with the warm tortillas on the side, letting everyone build their own fajitas.