Vue is much easier in that sense. You can just import the library using <script src"<<vue cdn addr>>"></script> and you can start using vue right there.
I'm working in a large GWT codebase right now and I have this fantasy where I convert the app to Vue or React. I think React hooks would complement a lot of the current components which are table rows or data-helpers. That said I haven't looked at Vue 3 very much which is adopting a similar function-based component pattern.