Heat olive oil in a large, deep skillet over medium heat. Cook and stir pork in hot oil until evenly browned and crumbly. Use a slotted spoon to remove pork to a plate, reserving juices in the skillet.

Add onions and garlic to juices in the skillet and cook over medium heat, stirring occasionally, until tender. Mix in peas, beans, mushroom, and bell peppers. Cook and stir until vegetables are tender and heated through.

Return pork to the skillet. Stir in tomato sauce; bring to a boil. Season with chili powder, marjoram, nutmeg, and salt. Reduce heat and simmer until chili thickens and flavors blend, about 45 minutes.