What does he mean by pre-rendering? Do they spin-up a browser-like environment on the server and use that to render the page and cache it? Or has that idea been improved upon?
At the end of your SPA build process, you spin up a dummy HTTP server and run headless chromium on it (e.g. with puppeteer) to render each route and save the output html.
Instead of only /dist/index.html, you have /dist/index.html, /dist/about/index.html etc.