A couple weeks ago I did my portfolio site with React/Gatsby, while its performance was relatively good and better than say a wordpress page, but later I tried Zola and the performance is just much much better, in development or even as a user, plus now it works even with no JavaScript enabled in the browser. So I think react and the likes can be used but only when it’s the only tool that can make it, else, there are plenty of better tools.
React and SSR are not mutually exclusive. I don't know what Zola is though and I like using static no-JS sites :)
Haven't used Gatsby but in theory every SSG should produce output that is usable without JS.
It all depends on the components then, which, well, shouldn't use client-side JS for rendering essential HTML if you want to work them without it.
Zola is a static site generator and it’s crazy fast, using one binary only [2], also there’s Blades [3], same concept but supposedly faster, never tried it though.