I can build your app using flutter as flutter is cross platform I can build android and ios both app in single code base and it can run smother than native apps and as flutter developer I can assure you I can archive all your milestones and as you mention you need developer for long term so if you hire me for this work it would be great to start our professional relationship also 

Let me introduce my self:-

I have 2+ years of experience with Cross-platform technology using Flutter and backend technology like php and I have strong command over MySQL, Push Notifications, Firebase, RESTful APIs & GraphQL APIs. And I have developed a wide range of mobile apps using the same and executed successfully with the high satisfaction of my past clients. 

I can build complex app and i can work remotely 

Below you can see a breakdown of my skills and experience:

Flutter development (Dart)

Android development (java)

Backend development(php/mysql)

Ios development (swift)

Testing

Project management