Bougainville's Status: An Autonomous Region of Papua New Guinea, Not Formally Incorporated

The premise is mistaken. Bougainville is not a province fully integrated into Papua New Guinea. Since the 2001 Bougainville Peace Agreement, it operates as an autonomous region with its own government, constitution, and a guaranteed non-binding independence referendum (held in 2019, overwhelmingly pro-independence). Final status awaits negotiations between Bougainville and the PNG national government.