The collecting organisation does, and that should hold by design rather than by goodwill. Data stays in the hands of the government that gathered it, a full export is always available, and the platform can be self-hosted from open source where a ministry wants complete independence.
Video: Webinar: Data Sovereignty in the Age of Cloud Computing and AI on YouTube
Many monitoring systems are built by a project, hosted by a contractor, and quietly lost when the funding cycle closes. The ministry is left with a PDF report and no database. Data sovereignty is the question of who can still read, export and run the system in five years, and it is far cheaper to settle before the first survey is collected than after.