Cross-Platform IoT Alert App

I’m looking for a lean, cross-platform mobile app that connects my environmental sensors to users’ phones through Firebase. The app must read each device’s data node in real time and, whenever a value changes, animate key UI elements so the change is impossible to miss.

Even with the phone locked, an alarm has to sound. Inside a settings screen the user will be able to add or remove devices and choose any combination of Ringtone, Vibration, and Pop-up message for their alerts.

Scope for this initial release is intentionally kept tight:

• Real-time Firebase link to multiple environmental sensors.
• Animated visual cue whenever data at a selected node changes.
• Background service that keeps alarms active on locked screens.
• Per-device alert options: Ringtone, Vibration, Pop-up message (individually toggleable).
• Clean, basic interface that works on both Android and iOS.
• Final deliverables: source code, brief setup README, signed builds ready for Play Store and App Store submission.

A single codebase using Flutter, React Native, or a similar framework is preferred so maintenance stays simple.