Adjust oven rack to center position and preheat oven to 350°F (175°C). Season chicken generously with salt and pepper. Heat oil in a sauté pan over medium-high heat until shimmering. Add chicken, skin side down, and cook until well browned and crisp, about 8 minutes total. Flip chicken and brown lightly on the second side, about 3 minutes. Transfer chicken to a large plate and set aside.

Return the skillet to heat without draining it and add sausage. Cook until well browned on the first side, about 1 ½ minutes. Flip sausage and cook on the second side until browned, about 1 ½ minutes longer. Remove pan from heat, transfer sausage to a cutting board, and cut each link into 3 to 4 slices.

Return pan to heat, add onion and bell pepper, and cook, stirring and scraping up browned bits until softened and starting to brown, about 4 minutes. Add sage and garlic, stir to combine, and cook until fragrant, about 1 minute.

Add pickled cherry peppers and their liquid, stirring and scraping up browned bits from the bottom of the pan. Add wine and cook until liquid is reduced by half, about 2 minutes. Add chicken stock and sugar, and stir to combine. Return sausage to the pan, toss to combine, then return chicken pieces to the pan skin side up, nestling them down among sauce, vegetables, and sausage.

Transfer to oven and cook until chicken is crisp and tender, about 30 minutes. Serve immediately, spooning sauce, vegetables, and sausage around chicken pieces.