Wouldn't any of those fit the case if you just do tree-shaking?

You have to specifically write code that supports that, so no. Look at the limitations of tree-shaking for more info.

Rebass.

Not sure what their bundle size looks like but my understanding is they're using PJAX so the site output should function without JS. Problem is good luck maintaining that stack and remaining secure. And then there's the fact there's no conceivable way it could scale properly for large sites static which would need something like Go/Rust to actually generate quickly then there's the matter of caching. Basically this all leads to headaches just in different places.