Heat the oil in a large skillet over medium-high heat.
Prick the sausages with a fork and cook, turning occasionally, until browned and just cooked through, 10 to 12 minutes.
Meanwhile, cook the bacon in a second large skillet over medium heat, stirring occasionally, until crisp, 3 to 4 minutes.
Add the onion and cook, covered, stirring occasionally, for 4 minutes.
Add the cabbage, apple, vinegar, 1/2 teaspoon salt, and 1/4 teaspoon pepper and cook, stirring occasionally, until the cabbage is just tender, 6 to 8 minutes.