Soak The Skewers. Before starting, soak the skewers in a bowl or shallow dish of water for at least 10-15 minutes (up to 2 hours). This will prevent them from smoking or burning when cooked.
Prep The Chicken. If you haven't already, cut the chicken into 1-inch cubes. Place chicken cubes into a shallow dish or container that has a lid so you can use it for marinating.
Make The Sauce. In a medium bowl or large liquid measuring cup, combine 3/4 cup pineapple juice, 1/2 cup ketchup, 1/2 cup tamari, 1/2 cup brown sugar, the garlic, and the ginger. Whisk until well blended.
Divide The Sauce. Set aside 1 cup of sauce for marinating, 3/4 cup for basting, and the rest for serving.
Marinate Chicken. Pour 1 cup of the sauce over chicken, cover, and refrigerate. Marinate chicken at least 2-3 hours, up to overnight. (Keep the reserved basting and serving sauce in two separate containers in the fridge to avoid cross contamination!)
Skewer The Chicken. When you're ready to cook, thread the chicken onto the skewers, leaving yourself a 1-2 inch "handle" at the end that you can use for turning or holding. Aim to pack the chicken pieces closely together without smashing them right up against each other. Discard the remaining marinade.
Baste. Brush the chicken skewers generously with about 1/3 of the basting sauce. (You'll still have plenty left!)
Air-Fry. Line the basket with a parchment paper liner. Working in batches so there's room for air to circulate around each skewer, cook the skewers at 350 degrees for about 12-15 minutes, pausing to flip the skewers and brush with another 1/3 of the basting sauce onto the them halfway through cooking. Repeat until all the chicken has been cooked to an internal temperature of 165 degrees F. Brush the remaining basting sauce on the chicken one more time and then turn up the heat to 400 degrees and cook an additional 2-3 minutes to caramelize the sauce.
Serve & Store. Serve chicken with extra sauce, white rice, pineapple, coleslaw, or macaroni salad. Store leftover chicken in the fridge in an airtight container 3-4 days.