Simple Customization of Already made Flutter App

The app is emulated from a CMS website through endpoints/API, so no fresh coding, everything is pulled from the main website [login to view URL] The app already had a messenger chat feature but it needs some slight modification such that... 2.0 Messages Realize messages (like in WhatsApp, including notifications on home-screen and with sound/vibration, etc.) 2.1 Contacts Synchronization ● Ask the user for permission to synchronize his phone contacts with the members of the platform 2.2 List known/matching members and entries in the phone as "contacts" (separate list) - technical and design guidance like on WhatsApp 2.3 Add buttons "new contacts" and "new group" ● realize the possibility to put each contact into a group (like on WhatsApp) 2.4 Establish a phone communication navigation area on top This navigation area on top includes the following items: i. Contacts ii. Messages (each sub-point with different colour and a number indicating the unseen messages) a. Official b. Friends c. General d. Settings (like notification, sounds for notifications, notifications on home-screen etc.) 2.5 Localization A list (same as "contacts'') "In my area" in which I see people out of my contact list and their airline/linear distance to me. 2.6 Show other members who are in my area Use the phone's location possibilities to show members who from their friends or just other members are in their area. Add the possibility to switch off: "don't show my location." 2.7 From this list on, I have the possibility to "write a message" and "view the profile" of the respective contact. 2.8 Handling of Official Messages can be sent by: i. Lecturers to students who attend a course of this lecturer ii. admins iii. DAAD people only in this cases the writer of a message gets a tick box where he can mark the message as official Please see the draft below.