Prick sweet potatoes all over with a fork. Microwave on high until tender, 8 to 10 minutes. Let cool until easily handled, about 10 minutes. Peel and mash sweet potatoes in a bowl. Mix in maple syrup. Season with salt.

Turn on an electric pressure cooker (such as Instant Pot®) and select "Saute" mode. Rub the turkey breast all over with the barbeque seasoning. Add 1/4 cup butter to the pot and allow it to melt and begin to sizzle, about 2 minutes. Place seasoned turkey breast in the pot, skin-side down. Cook until browned, about 5 minutes. Turn off heat.

Melt the remaining 1/4 cup butter in a skillet over medium heat. Add celery and onion; cook until slightly softened, about 2 minutes. Add cornbread, pecans, and bacon. Remove from heat; sprinkle with 1/2 teaspoon of barbeque rub. Stir cornbread dressing gently.

Create 2 rafts out of aluminum foil. Poke a few holes in 1 raft and fill it with the cornbread dressing. Fill the second raft with the mashed sweet potatoes.

Flip browned turkey breast skin-side up. Place cornbread dressing raft on top. Add stock, pouring it slowly over the dressing; it will drip down onto the cooking surface and keep turkey moist. Place the raft of sweet potatoes on top of the dressing.

Seal pressure cooker. Select the "Poultry" setting and set the timer for 30 minutes.

Release pressure naturally according to manufacturer's instructions. Let turkey breast rest for 5 minutes before slicing. Serve on a platter with cornbread dressing and sweet potatoes.