Me and a friend have been working on this small framework that wraps esbuild (https://esbuild.github.io/), it adds a few javascript tags like <Router> and <Head>, then pre-renders pages with headless chrome and spits out a high performance webserver that can forward traffic to another website.
It's built so that you can do "start": "concurrently 'greenjs start -upstream-addr :8000' 'rails dev'" or equivalent for another web framework