I absolutely love that this can be hosted on Github Pages. Am I correct in understanding that these notebooks will run independently, and will not need to proxy through marimo.app (in case the app goes down), or is that what the CORS thing is about in note 4, and it will still need to go through this domain?

Yea, this can be hosted on GitHub pages without any vendor infra (no marimo.app)

These are two separate features:

1) marimo.app + github.com/path/to/nb.ipynb does run on marimo.app infra. this is what the Show HN was about

2) separately, you can use the marimo CLI to export assets to deploy to GitHub page: `marimo export html-wasm notebook.py -o output_dir --mode run` which can then can be uploaded to GH pages. This does not find all the data in your repo, so you would need to stick any data you was to access in a /public folder for your site. More docs here: https://docs.marimo.io/guides/exporting/?h=marimo+export+htm...