Heat oil in a large skillet over medium-high heat and brown sausage links for 2 minutes per broad side; they will finish cooking in the slow cooker. Transfer to a 6-quart cooker.
Soften onion in the skillet for 5 minutes, add garlic for 1 minute and pour in wine, scraping up the browned bits. Transfer to the cooker with passata, the 1 1/2 cups broth, oregano, salt and pepper.
Cover and cook on low for 6 hours until the sausage centers reach 160°F and the links are tender. Lift sausages to a covered plate and turn the cooker to high.
Stir pepper strips and dry rigatoni into the hot sauce, pressing the pasta into the liquid. Cover and cook for 30 to 40 minutes, stirring after 15 and 25 minutes, until the tubes and peppers are tender.
Add some of the measured extra hot broth only if the pasta is still firm and the sauce is nearly absorbed. Slice cooked sausage into thick coins, fold them into the pasta and cover for 5 minutes until the sausage reaches 165°F.
Switch off and divide among six bowls, distributing the sausage coins and both colors of pepper evenly.