We've only shipped a helper library for Preact, but the Prerendering is actually generic. Some folks are working on helpers for other frameworks. The "API" is just a function exported from your first script tag:

export async function prerender(data) { return { html: "<h1>hi</h1>", links: ["/other-page"] } }

Hot reloading is a similar story, it's the same API as Vite and Snowpack:

if (import.meta.hot) import.meta.hot.accept(({ module }) => { do stuff }));