Transfer the chicken breasts to a large gallon-size bag or a baking dish.
Prepare the marinade. Add the soy sauce, ketchup, pulverized pineapple, pineapple juice, honey, vinegar, and sriracha to a bowl and whisk the ingredients together until combined. Pour half of the marinade over the chicken and set the rest aside for later. Refrigerate for at least 30 minutes or up to 2 hours.
When ready to grill, remove the chicken from the fridge and let it rest for 10-15 minutes. Preheat the grill to 450ºF. Clean the grill grate off or lay a piece of aluminum foil on the grill.
Season the pineapple with chili powder and salt.
Transfer the marinated chicken to the grill over direct heat and grill for 8 minutes per side.
Grill the pineapple for 2-3 minutes per side over direct heat or until the pineapple develops grill marks. Remove from the grill.
While the chicken is grilling, pour the remaining chicken marinade into a saucepan along with the rest of the marinade you set aside earlier. Bring to a boil over high heat. Turn the heat to low and allow the marinade to simmer for 2-3 minutes. Remove from heat.
Remove the chicken from the grill when the internal temperature reaches 165ºF.
Serve the pineapple over the chicken and pour the remaining marinade over the chicken and pineapple. Serve immediately.