Here is a recent application of the converter related to my "LLM aids for processing of the first Carlson-Putin interview" series of posts.

1. Make the Raku Jupyter notebook
   • With the LLM aids for the Carlson-Putin interview
2. Convert the Jupyter notebook into Markdown
   • Using Jupyter's built-in converter
3. Publish the Markdown version to WordPress
4. Convert the Markdown file into a Mathematica notebook
   • Using the featured Raku package, "Markdown::Grammar"
   • The obtained notebook uses "RakuMode"
5. Publish that to Wolfram Community
   • It was deleted by moderators, because it does not feature Wolfram Language (WL)
6. Make the corresponding Mathematica notebook using WL functions
7. Publish to Wolfram Community
8. Make the Russian version with the Russian transcript
9. Publish to Wolfram Community
   • It was deleted by moderators, because it is not in English
10. Convert the Mathematica notebook to Markdown
    • Using Kuba Podkalicki's M2MD
11. Publish to WordPress
12. Convert the Markdown file to Jupyter
    • Using jupytext
13. Re-make the workflows using Raku

Here is the corresponding Mermaid-JS diagram (using the paclet MermaidJS or the function MermaidInk):

ResourceFunction["MermaidInk"]["
graph TD
  A[Make the Raku Jupyter notebook] --> B[Convert the Jupyter notebook into Markdown]
  B --> C[Publish to WordPress]
  C --> D[Convert the Markdown file into a Mathematica notebook]
  D --> E[Publish that to Wolfram Community]
  E --> F[Make the corresponding Mathematica notebook using WL functions]
  F --> G[Publish to Wolfram Community]
  G --> H[Make the Russian version with the Russian transcript]
  H --> I[Publish to Wolfram Community]
  I --> J[Convert the Mathematica notebook to Markdown]
  J --> K[Publish to WordPress]
  K --> L[Convert the Markdown file to Jupyter]
  L --> M[Re-make the workflows using Raku]
  C -.-> WordPress{{Word Press}}
  K -.-> WordPress
  E -.-> |Deleted:<br>features Raku| WolframCom{{Wolfram Community}}
  G -.-> WolframCom
  I -.-> |\"Deleted:<br>not in English\"|WolframCom
  D -.-> MG[[Markdown::Grammar]]
  B -.-> Ju{{Jupyter}}
  L -.-> jupytext[[jupytext]]
  J -.-> M2MD[[M2MD]]
  E -.-> RakuMode[[RakuMode]]
"]

The blog post "Conversion and evaluation of Raku files" proclaims a presentation made with Mathematica that shows conversion of a Markdown file into a Mathematica notebook and a Jupyter notebook.

Ideally, the program jupytext will be extended to deal with Mathematica / WL notebooks.

Here is the presentation at YouTube:

I did not know about Connor's package "md2nb" -- thanks for pointing that out!

(If I knew about it, most likely I would have not written my "Markdown::Grammar" package.)

Nice, glad to see this!

Thanks!

If I wanted to convert the markdown doc into a WL Tree, is it as simple as passing the generated Notebook object to ExpressionTree? Or would I need to do something with the grammar directly?

I am not sure what you are asking -- I think you are interested in some form of the Abstract Syntax Tree (AST) of the Markdown document.

Of course, we can treat the obtained notebook expression as AST in the way you describe, see the attached screenshot.

If you have Raku installed then you can obtain the AST of the markdown document with the package command md-parse.

Warning: Installation of Raku on macOS (using rakudo.org) might be not that easy. I advice using rakubrew.