The latest release of FeedLand Rivers for WordPress implements Instant Updates. Similar to FeedLand itself, the rendered river uses websockets to listen for new and updated items and will update the river. It still uses no styles or scripts not bundled with the plugin itself.
I've released a WordPress plugin that shows a FeedLand river on a page or post: feedland-rivers.
Drop the shortcode `[feedland-rivers]' onto a page, point it at your FeedLand username in the settings, and it fetches the river JSON server-side and renders it in an isolated iframe. No FeedLand front-end scripts, no third-party fonts or stylesheets beyond an optional favicon lookup. Here is an example.
You can also show more than one river on a site by overriding the username, category or server per shortcode instance, e.g. '[feedland-rivers username="alice" category="tech"]'.