No, Druid does not delegate to system widgets as far as I know. In that sense, it's slightly wrong that it's called "native", as it's not native UI, but it's compiled "native code" (= not Electron or a wrapper to some other framework that's written in some other language).

Here are the goals of Druid; be sure to read about the non-goals too: https://github.com/linebender/druid#Goals