Real-Time Command Blocking App

I need a mobile app that can instantly intercept and block any command issued on a user account. The solution has to run on both iOS and Android and work the moment a text or voice instruction is detected, cancelling it before it reaches the underlying service.

Core goals
• Sub-second response: once a command is issued, the block must take effect in real time.
• Universal coverage: text, voice, or any other command format should be handled without extra setup.
• Seamless integration: the blocking mechanism has to sit between the user interface and the target account or API, preventing the original request from being executed while logging what was stopped.

I am open to your suggestions on the best tech stack—React Native, Flutter, native Kotlin/Swift, WebSockets, Firebase, custom backend, or whatever you feel will guarantee speed and reliability. If you believe an admin dashboard or analytic panel would add value, please outline how you would implement it and what extra effort is involved; I have not decided on that yet.

When you reply, briefly describe:
1. How you will achieve instant interception on both platforms.
2. Which libraries, frameworks, or cloud services you would choose and why.
3. A high-level timeline to reach a working proof of concept.

I’m looking for a clean, well-documented codebase and thorough testing so we can move quickly from PoC to production.