Whisk together the pineapple juice, oil, soy sauce, salt, brown sugar, hot sauce, and mustard.
Place chicken is a large sealable bag and pour in the marinate. Marinate in the fridge for 4 hours.
When ready to cook, head grill to medium heat. Remove the chicken from the bag and discard the marinade.
Place chicken on the grill and grill 4-5 minutes per side. Add the pineapple slices after you flip the chicken and flip them after 1-2 minutes.
Temp the chicken with a digital thermometer to ensure it reaches an internal temperature of 165°F. Place a slice of cheese on the chicken when there is about a minute of cooking time left to allow the cheese to melt.
Remove chicken and pineapple from the grill. Spread mayo evenly on each side of the bun (about 1 ½ tsp for each sandwich). Place chicken on the bun and top with grilled pineapple slices.
Serve and enjoy.