Place dried mushrooms in a medium bowl and pour enough boiling water to cover. Let soak, undisturbed, until softened, about 20 minutes. Strain mushrooms, reserving soaking liquid for another use. Roughly chop mushrooms, set aside.

While mushrooms soak, heat a large Dutch oven over medium. Add bacon; cook, stirring occasionally, until brown and crispy, 7 to 8 minutes. Transfer bacon to a paper towel-lined plate using a slotted spoon; reserve drippings in Dutch oven. Do not wipe Dutch oven clean.

Add oil to reserved drippings in Dutch oven and heat over medium-high until shimmering. Season pork with pepper, and 1 ½ teaspoons salt. Add pork to Dutch oven; cook, turning occasionally, until evenly browned, 10 to 12 minutes total. Transfer pork to separate plate; set aside.

Add cabbage, onion, and remaining ½ teaspoon salt to dripping in Dutch oven; cook over medium-high, stirring often and scraping bottom with a wooden spoon to release browned bits, until cabbage is soft, about 4 minutes. Return pork along with any accumulated juices to Dutch oven. Stir in 4 cups water, sauerkraut, kielbasa, beer, juniper berries, bay leaves, and reserved mushrooms.

Bring to boil over medium-high. Cover and reduce heat to low. Cook, stirring occasionally, until pork is tender but not yet fork tender, about 1 ½ hours. Stir in prunes. Cover and cook, stirring occasionally, until pork is fork tender, about 30 minutes. Discard bay leaves. Remove from heat and stir in crispy bacon. Serve garnished with dill.