I also like Svelte's interactive tutorial, and this seems a cool idea.

Three years ago, when I started studying Nostr I had a similar idea and created https://github.com/dtonon/nostr-ruby-playground to guide myself (and maybe others) to learn the basics step by step.

It's not so fancy like an online interactive tutorial, but I think it's fine, and it is also easily scalable with more languages.

(then the code has been refactored and improved in https://github.com/dtonon/nostr-ruby)