Preheat oven to 425°F.
In a large Dutch oven or oven-proof stock pot, heat the olive oil over medium-high heat until shimmering. Add the onions and cook over medium heat until softened, about 5 minutes.
Add bell pepper and continue to cook over medium heat, stirring occasionally, another 5 minutes.
Reduce heat to low and add the garlic, stirring until fragrant, about 15 seconds. Add the chicken broth, scraping up any brown bits on the bottom of the pot.
Stir in the rice, saffron, red pepper flakes, salt, and pepper. Bring to a boil. Cover and place in the oven. Bake for 15 minutes.
Remove from the oven, stir rice gently, and layer the shrimp on top. Cover and return to the oven until the rice is tender and the shrimp are bright pink and cooked through, 10 to 15 minutes longer.
Transfer the Dutch oven to the stove top over medium heat and add the liquor. Continue to cook until the liquor has been fully absorbed by the rice. Remove from heat and add kielbasa and peas, stirring carefully to combine.
Cover and allow to steam until the kielbasa and peas are heated through, about 10 minutes. Sprinkle with parsley, serving the lemon wedges on the side.