In a large bowl, whisk together 1/4 cup (60 ml) of the reserved pineapple juice, olive oil, honey, minced garlic, cumin, 1 teaspoon of kosher salt, and black pepper.
Add the chicken breasts to the marinade, turning to coat them evenly. Let the chicken marinate at room temperature for 30 minutes, or cover and refrigerate for up to 4 hours.
Rinse the white rice under cold water until the water runs clear. Combine the rice, water, and remaining 1 teaspoon of kosher salt in a medium saucepan. Bring to a boil, then reduce the heat to low, cover, and simmer for 15 minutes or until the water is absorbed. Remove from heat and let it sit covered for 5 minutes.
Preheat your grill or a grill pan over medium-high heat.
Grill the marinated chicken for 6 to 8 minutes per side. The chicken is done when a meat thermometer inserted into the thickest part reads 165°F (74°C). Transfer the chicken to a cutting board and let it rest for 5 minutes before slicing.
Place 5 of the pineapple slices on the grill. Cook for 2 to 3 minutes per side until grill marks appear. Remove and chop the grilled pineapple into small pieces.
In a medium bowl, combine the chopped grilled pineapple, red onion, jalapeño, cilantro, lime juice, and avocado. Toss gently to mix.
Divide the cooked rice among five bowls. Top each with the sliced grilled chicken and a scoop of the pineapple salsa.