I am looking for an experienced developer (or a team) to realize the software side of a unique intercom project. We are building the hardware unit ourselves (custom design) but need to connect this with a modern app solution for the residents. I would like you to propose the best architecture, but the solution must be based on the following core components and functionality: 1. Door Unit (Client A) *The hardware at the door is a Raspberry Pi with a touch screen, camera, and microphone. *The application here must run in "kiosk mode". *The unit must be able to control a relay for door opening via GPIO pins. 2. Communication (Critical) *The solution must support two-way real-time audio and video. The proposed standard to be used is WebRTC. *A distinction must be made between signaling (connection setup) and the video stream itself. 3. Mobile App (Client) * An app must be developed for the residents that supports both iOS and Android (preferably via Webapp, Flutter, or React Native for a shared codebase). * To ensure the resident receives the call even if the app is closed, the solution must include reliable "wake-up" via Push Notifications (e.g., Firebase/FCM). * The mobile app must have a user interface and an administration interface (add/remove users, phone numbers, number of users, etc.). Your Freedom in the Task: Beyond the points above, you are free to choose the backend language (e.g., Node.js, Python, or other), server hosting, and specific libraries, as long as the result is robust and user-friendly. If you are interested, please send me an estimate or a proposed solution based on these requirements.