If you run EIN (Emacs Ipython Notebook module) in emacs with vim keybindings (via spacemacs or evil mode, or some other distribution/mode) you can get some pretty great results. Would definitely look into it if you're either already using emacs or willing to try it out.

I tried it at some point, but a minor inconvenience was that it kept adding superfluous metadata to the cells I was editing.

Since some of the notebooks I work on are collaborative and versioned with git, this was painful for reading diffs (even more so with the ipynb format) so I dropped it to my regret.

It's far from perfect, but I use jupyterlab with the jupyterlab-vim extension for this: https://github.com/jwkvam/jupyterlab-vim

Not just keybindings. I don't know how your Vim setup looks, but my Emacs setup gives me some extra "non-default" tools that are consistent across the whole program, whether I'm editing Lisp, JS or managing files in a directory. Two that I use daily are semantic select (you press a key to expand your selection to the nearest encompassing semantic unit) and multiple cursors.

I did spend several days in a row typing code 10+ hours a day in Observable notebook (I had some idea I needed to validate and demonstrate to other people in the company). While the tool itself was amazing, the coding aspect was not.

qutebrowser had a keybinding for opening things in vim IIRC