Maybe to reformulate the question more: is the overhead of the default Unity3D layer is a big battery consumption?
Imagine an equivalent app developed with Xcode/AndroidSDK vs Unity. The app could be a shoot them up with a app-style UI (eg: material design), and using the GPS (why not ?). Let say UI and games graphics will both use Metal (or equivalent on Android if it exists)
Is the delta consumption will be more close to 90% or 10% ?
You need to sinuously consider unity3d pro and cons and compare them to what you want from it i talked about it with you in comments but it's best to download some of unity3d created games and try them yourself
and there is a complete discussion about advantage and disadvantage of using unity here