Cook bacon in a 12-inch heavy skillet over medium heat, stirring occasionally, until crisp, 6 to 8 minutes. Add oil and onion and cook, stirring occasionally, until onion is golden, about 12 minutes. Add garlic, kosher salt, and 1/4 tsp pepper and cook, stirring occasionally, until garlic is softened, about 2 minutes. Add tomatoes, tomato purée, and thyme and simmer, uncovered, stirring occasionally, until sauce is slightly thickened, about 30 minutes.