Season both sides of the chicken thighs with salt and set aside while you make the sauce.
Set the Instant Pot to saute on high, then add ketchup, brown sugar, chipotle chiles, molasses, Worcestershire sauce, apple cider vinegar, garlic, paprika, pepper and dried mustard. Cook, stirring occasionally, until the mixture darkens and thickens to a paste (4 to 5 minutes). Stir in the chicken, cover and cook on high pressure for 15 minutes. Let pressure release naturally.
While the chicken is cooking, prepare the slaw. Add vinegar, sugar and salt to a large bowl, whisking to combine. Add green onions and cabbage to the bowl, tossing to coat in the vinegar. Let sit at room temperature until you are ready serve, tossing occasionally. Season to taste with more salt and freshly ground pepper right before serving.
Using tongs, transfer the cooked chicken to a bowl, leaving any liquids in the Instant Pot. Return the Instant Pot to saute on high, and reduce the remaining liquids to a thick sauce (like the texture of a BBQ sauce). This should take 5 to 10 minutes. While the sauce is reducing, shred the chicken. Toss the chicken with some of the BBQ sauce. It should be evenly dressed in the sauce, but not swimming in it. Season to taste with salt. Serve remaining sauce on the side.
To serve, pile shredded chicken on a slider bun, then top with slaw.