iOS Style UI in Unity? Plugin advice?

Hi, I'm a developer on an app at a tech company and we're building an iOS app in Unity. Right now I'm doing some research to try and find if there's a way to design using native iOS UI features from within the Unity app. I've found two plugins, but both seem a little under-supported and have mostly negative reviews:

iOS for Unity UI

MustHave iOS Kit for Unity

I was curious if anyone has tried to use these plugins before, and what success they've had if so? Any ideas about compatibility with Unity 5 or different versions of iOS? And then more largely, has anyon eelse tried to tackle this problem of designing a really polished UI inside an iOS app before? Any advice for developing iOS-level polish in UI rather than just building it from scratch myself?

Also, before anyone asks haha, we're building the app in Unity rather than native in iOS because we're using an AR plugin that's not supported in native iOS.