I have tried out Clerk yesterday and was really satisfied with the plug & play setup, the simplicity of the approach (no need to change anything in source files

I have tried out Clerk yesterday and was really satisfied with the plug & play setup, the simplicity of the approach (no need to change anything in source files, just add markdown in comments) and all the features (Hiccup, TailwindCSS, LaTeX, data vis., etc.) it provides out of the box. But of course it is not a social/collaborative platform like Observable (though I believe you can host your compiled notebooks on your own server). But the developer of Clerk and some others also created a platform for Clojure-based reactive notebooks that seems especially great for learners and teaching: https://www.maria.cloud https://www.maria.cloud It has a picture language, evaluation of sub-forms, basic structural editing and is really beginner-friendly.