That doesn't really parse. React as a thing is some pretty thin DOM manipulation and some helper stuff. Are you thinking of something like Next or some all-in React+Redux stack?
As misfortune would have it, I spent a significant fraction of the day reading the implementation of hooks for fibers. There's nothing light weight about virtual Dom, reconciliation, and micro task queues.
You mean a normal react build?
This is what Svelte does, React has a runtime even when bundled