Everything is cooked in batches in this one-pan dish that works equally well for breakfast or dinner: the bacon first, followed by the herbed potatoes, garlicky greens, and scrambled eggs.
Cook bacon in a large nonstick skillet over medium-high heat until fat begins to render, about 2 minutes. Add 3 tablespoons oil, potatoes, onion, chard stems, and rosemary; season with salt. Cook until potatoes are tender and browned in places, 13 to 15 minutes. Stir in chard leaves and garlic, season with pepper, and cook, stirring a few times, until leaves are tender, about 3 minutes. Transfer to a serving dish; loosely cover to keep warm.
Add remaining 1 tablespoon oil to skillet and place over medium heat. When oil shimmers, add eggs, season with salt, and cook, stirring frequently, until just set, about 1 minute. Serve with potato mixture and salsa.