A freedrive mode is on the list of good ideas already. But if ever, it will be based on the (here) navigation engine and not on the mainscreen map (OSM). It will not be ready for release date, it will be a function that might get added later.
Many countries have their own "best radar app" and they are all different. And they probably all want your money if you want to embed it in another software. So it is a difficult thing.
Nice idea, but with limited value. Most route planners plan their routes weeks before they actually are driven. Weather forecasts a quite meaningless in that stage. It might be better to have it in the app instead of the planner. So you can check your route for rain on the day that you want to go for a ride.
This will most likely be "smoothened" before release.