Place the chicken thighs and chopped red bell pepper, yellow bell pepper, pineapple rounds, and yellow onion into a gallon-size bag (or two).
Mix together all the marinade ingredients in a bowl (pineapple juice, coconut aminos, avocado oil, garlic, ginger powder, sriracha, salt, and pepper). Whisk until smooth.
Dump the marinade into the bag with the veggies and the chicken. If you split this into two separate bags, be sure to divide the marinade into both bags.
Let the chicken and veggies marinate for up to 2 hours.
When you are ready to cook, heat your grill to medium-high heat. Spray or drizzle your grill or griddle with your favorite non-stick spray. Add the chicken to one side and then add veggies to the other (or to the grill pan if you are using a regular grill). If you have a Blackstone grill, you can dump some of the marinade onto the grill with the veggies, but if you are using a regular grill, do not do this.
Cook the chicken for 5 minutes on one side, then flip it for another 5 minutes on the other side. Repeat this until the chicken has reached an internal temperature of 165°F. This should take about 20 minutes.
Move the veggies around until they get a slight char on them. This should take 10-15 minutes depending on if you added the marinade or not.
Remove everything from the grill, serve, and enjoy!