You can give Starboard Notebook [0] a shot (a tool I'm building). It doesn't have reactivity which is as powerful as Observable - it's closer to normal web programming.

Here's an example notebook that shows p5.js use (with Python interop as a bonus): https://starboard.gg/nb/n3DYopT

It supports local or self-hosted editing and viewing [1] and is all open source.

[0]: https://starboard.gg [1]: https://github.com/gzuidhof/starboard-notebook and https://github.com/gzuidhof/starboard-cli