Cross-Platform MQTT Client App

I need a developer to create an MQTT client app for both Android and iOS platforms. The app should allow users to both subscribe to topics and publish messages.

Key Requirements:
- Subscribe to text message topics
- Publish text messages
- Simple and minimalistic UI

Ideal Skills and Experience:
- Experience in mobile app development for Android and iOS
- Proficient in MQTT protocol
- UI/UX design skills for creating minimalistic interfaces
- Familiarity with cross-platform development frameworks (e.g., Flutter, React Native) is a plus