I totally agree that we need a standard -- but it is already here: markdown files with YAML frontmatter, github-style checkmarks and hash-tags. All synced via your favorite filesystem synchronizer.

This is supported by the tool discussed here (`nb`), and over the last 20 years, I have used it with all these tools:

  - Notational Velocity (macOS)
  - Resoph Notes (MS Windows)
  - nvPy (cross platform)
  - Obsidian (cross platform)
  - 1Writer (iOS)