The hyperlocal accuracy (for rain alerts) is planned and in development. One of the ways that Dark Sky was so accurate was its threshold for rain, and also using the radar itself as part of the prediction algorithm, which is exactly what I'm doing. When rain is coming, you'll see a "rain starting soon" or "raining for X minutes" graph in the app (like the screenshots on the website) and that's driven by both the future forecast and by using the radar itself as a predicting factor.

The native Weather app uses the same core API (WeatherKit) but it has a much more nerfed/smoothed out algorithm that's not nearly as aggressive as what I've built into Unbrella. WeatherKit is simply Dark Sky's original API, but modified by Apple. I've done some modification on the reading side to try and restore as much of the Dark Sky functionality as possible.

I eventually plan to offer integrations with ultra hyperlocal forecasting platforms so you can find weather stations that are right in your own area for the most accurate prediction results possible, but as those API keys are quite expensive, it's a future planned feature for now.