I have recently migrated from OneNote to Joplin and was not satisfied by the 2-step migration OneNote -> EverNote -> Joplin, in particular due to the lost of my Section hierarchy and Page ordering.
So I developed a Windows Console Application that directly export OneNote notebook into RAW Joplin Folder Directory.
The tool can be downloaded in the GitHub repository GitHub - alxnbl/onenote-md-exporter: ConsoleApp to export OneNote notebooks to Joplin and other Markdown formats , section "Releases" on the right of the page. A comparison between the migration based on this tool and the one on EverNote is also provided.
Hope it will help other users to take the great leap forwards . Please open a GitHub issue if you encounter any error or formatting issue.