How is Vite relevant to the discussion? It's like saying the UI based on Visual Studio is lighter.
Because Vite emphasizes "Optimized build" in their marketing
Slower builds might make developers more thoughtful of the bloat, but I still think it’s tangential.
That said, how does Nue compare to, say, Svelte?
I'm not sure if I got this correctly, but it seems like you're misunderstanding what Vite actually is or does.
For having built what is essentially a bundler, I would've guessed you were more familiar with what it does, or, perhaps even have used it to build your tool.
Vite can bundle framework-less html files. It can create an SPA without any JS faff. You just have to point it to the right direction. When you instantiate a Vite app, you have to make the conscious decision to use React under the hood.
As for Nue, I think it's a cool idea, but I don't see what it does that I couldn't do with Astro, which has way larger community support and can work with pretty much all JS frameworks OOB.
BTW, I think it's really disingenuous to compare a React SPA bundle with an SSG output. You have essentially no functionality for handling state mutations beside events. You could achieve a much better middle ground by using a compiled framework like Svelte or Solid.