I wonder if Trilium Notes and the journal functionality would address your needs. You can use tags and backlink to other related notes if you wanted to. You can view notes in a standard hierarchy structure or view a note map.

You can take it a step further if that doesn't completely address your needs by customizing it. The journal button is just a note with a script (with a specific tag). It's highly customizable.

You can export your notes (all, or get granular with some or a single note) as HTML or Markdown or OPML.