This looks like an interesting project, coming from another minority language - Raku - I can see how dogfooding like this is a great way to try and help Julia break into the Python hegemony (yawn) esp. in academic circles. otoh, I am not sure that a pure play Julia notebook thing is long run better than a pure play Python thing (Jupyter ofc).
Yet notebooks are a vital angle for any scripting language. So I guess I would like to see a language neutral notebook platform with pluggable kernels. Meantime Jupyter does that pretty well and, with Raku Inline::Python support for pip modules can be a lot of fun with a Raku kernel, especially with LLM chatbook use cases.