Trying to understand what's different between this and approach non-js backend langs have been doing for 10 years. Server side rendering and resume by rendering different <head> on demands of different resource (url).
It looks like you can build an app using the convenience and rich interactions of React-like abstraction while gaining the benefits of a traditional backend approach. If so, I’m sold. I love React, but hate the SPA pitfalls and bloat.
React (react-dom) is also bloat, though. The only selling point of React is being popular which brings some benefit. I'd say we are "stuck" like having to use a legacy machine just because parts for maintenance is widely available.
JSX is fair, though ugly. Every programming language has function and they can compose even better in nicer way. Also other ways of doing state rather Hook hack which is yet another external-tool coupling dependencies.