Just tried the site, and already the first problem is isn't as interactive as the Websites for any JavaScript framework, because naturally there is a whole contraption to make the code run into the browser.
https://react.dev/learn/tutorial-tic-tac-toe
Where editing the code, immediately shows the GUI related changes on the neighbouring frame.
While what I see on https://leptos.dev/ is just screenshots, and there is nothing on that documentation you linked that provides the same interactive experience, one has to explicitly start a developer sandbox to host the whole machinery, and even requires a codebox account for editing.