Cross-Border Grocery List App

I need a complete mobile application that lets someone living abroad type in the groceries their relatives back home need, then share that list instantly. The build has to run smoothly on both iOS and Android, using a single code-base if it keeps costs and maintenance in check... (Budget: $250 - $750 USD, Jobs: Agile Development, Android, Android App Development, Flutter, iOS Development, iPhone, Mobile App Development, PhoneGap)