Native Android and iOS mobile developer Offline

English: C1 
9+ years of experience 

A set of IoT projects, currently we are integrating Voip functionality for the Cardo Systems team (they make software for helmets for motorcycles and the like).

First person I’m looking for is a super skilled mobile developer (either Android or iOS)
Someone that can single handedly lead a project, go into complicated stuff etc
We are rewriting a large app. Building it from scratch
Need to enter a very large code base , understand what is relevant and what isn’t
Must have perfect English
it’s iOS & Android project involving hardware
I think it’s all swift but not sure .. maybe there’s objC. UI is a mix between UIKit and SwiftUI