I wish that the notebooks supported Typescript or C# or something I'm more familiar with, out of the box.
For C# I have LinqPad, which I'm a huge fan of but never discovered something with similar functionality for typescript.
I've seen some open source kernels[0] but I'm not sure about the quality, did anyone try them? Deno core in Jupyter would have been amazing.
[0]: https://github.com/jupyter/jupyter/wiki/Jupyter-kernels
For C#, have you seen .NET Interactive[0]?