I’m partial to the idea of converting Mercury into a star lifter / thruster / planetary shade. Blocking sunlight to Venus would cause the atmosphere to cool, then freeze and fall as snow. Then you can disassemble Venus too for more raw material. That’s a massive store of carbon, oxygen, and sulfur. Solar powered mass drivers operating out of a planetary vacuum cut costs of launching material into space.
People often object to the idea because we can’t afford it, it’s too difficult, or out of concern for preserving those planets. Yeah, we won’t be doing all that. It will be our descendants in the far future. A task for new civilizations, over eons. Discovering life on Mercury and Venus is a long shot. But if it is there, it’s doomed without human intervention. Convert those two planets to Dyson swarm, and they’ll have matter for countless orbital habitats, not just for whoever humans evolve into, but for nature preserves too.