Out of curiosity, why is it unacceptable. It’s a great product with founders who have given much to opensource.
Best option atm seems to be Pluto or Jupyter.
ObservableHQ like instance with some basic auth controls would be perfect.
It embeds an observable runtime in a standalone electron app. The interface is not a notebook but rather a dashboard where you can add observable nodes of various sizes. It also has tabs. I find it a lot more manageable for large notebooks, and a lot more user-friendly for business use cases.
Also the standalone app means you can connect to databases and filesystems directly, and avoid CORS for rest apis.
If you’re interested in becoming an early adapter, drop me a line at the email on the website. I’ll be happy to prioritize features that you’d need.
see https://observablehq.com/@tomlarkworthy/firebase
or a full example
Doesn't take anything away from the awesome product they built, it's just what it is.