As others here have remarked, a PWA is a term with a specific meaning: it was coined with the advent of the Service Worker API to refer to any webapp using the service worker cache.

However, that still doesn't rule out producing a "progressively enhanced" progressive web app. In fact, React (which this project uses) makes progressive enhancement even easier with ReactDOMServer and the componentWillMount/componentDidMount differentiation. So the downvotes are particularly unwarranted.