Is it possible to use MyST-NB to parse/render ipynb directly without Sphinx?

[choldgraf]

I was just chatting with @yuvipanda about how nbconvert is super heavy-handed when all you want to do is parse ipynb and then output to HTML. I wonder if it's possible to just use MyST-NB for this, without using Sphinx. I'd imagine a Python API that's similar to markdown-it-py, but that could parse ipynb. We have some Python API docs but it's not super obvious whether those can be used outside of Sphinx.

@chrisjsewell do you know if this is already possible out of the box? Or something that we would consider in-scope for the project?