In a mixing bowl, whisk together 1/4 cup BBQ sauce, 1/4 cup Sriracha, 1/4 cup honey, 2 Tbsp Dijon mustard, and 1/4 cup pineapple juice until smooth.
Place the 4 boneless skinless chicken breasts into a resealable plastic bag or shallow container and pour the marinade over them, fully coating each piece.
Seal the bag and refrigerate for at least a few hours or up to overnight to marinate.
Preheat the grill or a cast iron grill pan to medium-high heat and oil the grates or pan lightly.
Remove the chicken from the marinade, letting excess drip off, and discard the used marinade.
Grill the chicken for about 15 minutes, turning occasionally, until an instant-read thermometer inserted into the thickest part reads 165°F and the chicken is cooked through.
Transfer to a plate and let rest a few minutes before serving.