If you checkmark Offline Mode in the Dynalist desktop app, any document you then create will be stored locally only. That’s why that feature was released - a user had the same request as you.
The hierarchal structure and metadata is all there in json in the .data files, one file per document, and the markdown is in the fields. But basically you can move those files around and they’ll show up in the offline app.
Logseq is the next closest offline markdown outliner. There aren’t many other options out there, last I looked.