Place frozen chicken breasts in the bottom of the Instant Pot.
Add Worcestershire sauce, BBQ sauce, teriyaki sauce, lemon juice, garlic salt, and minced garlic on top of chicken.
Pour in water, but don't mix it in with the sauce.
Place the lid on top of the Instant Pot and move the valve to SEALING. Press the MANUAL (PRESSURE COOK) button and set timer for 18 minutes.
When the timer is done, let the pressure do a NATURAL RELEASE for 5 minutes. Then move the valve from sealing to VENTING and let the rest of the pressure release.
Remove chicken from Instant Pot and shred using 2 forks (it should fall apart fairly easily). Place shredded chicken back in the Instant Pot with all the juices and stir together.
To make coleslaw, combine mayonnaise, apple cider vinegar, sugar, mustard, and pepper, in a large bowl. Add your shredded cabbage.
Place a scoop of shredded chicken on your bun and top with a scoop of coleslaw. Top with extra barbecue sauce if desired and serve.