Cross platform classifieds ads application Flutter + Xamarin

*********NOTE: My first choice is Xamarin, if not, Flutter is the alternative********* Please before submitting your bid, take your time to download and explore/test the functionality of the application, to be clear of the requirements and my expectations in this project, and consider preparing an estimate for the time required for each stage and for the whole project. I’m looking for a full-stack developer/team to build a cross-platform CLASSIFIEDS ADS application(IOs/Android) + website + API using Xamarin(C#)/Flutter The application should in MINIMUM cover the main following aspects: - Ads (Title, Description, Images, Status, Expiration, Views, Likes, Share, Comments, Reports, Followers, make an offer, Exchange items, ..etc ) - Categories and custom fields/properties for each category - Advanced Search includes different criteria (Keywords, categories, distance, price, customized search based on each category custom fields/properties..) - User (Registration flow, Profiles, Sales, Expired, Selling, Rating, Reviews, favorites, Status, Addresses) - Registration flow(Email, mobile, google) - Messages/Chat and notifications - Images - Common Settings (Countries, Cities, Coordinates, Currencies) - Plans, subscriptions, and payments I’m aiming for something similar to Letgo in functionality, so PLEASE, PLEASE take your time to download and explore/test the functionality of the application, to be clear of the requirements and my expectations in this project For the back end, .Net is my 1st choice, and I’m open for using Firebase or Azure Images upload can be stored on AWS A developer/team with previous experience in classifieds apps will be more preferred Source code should be well documented and shared during the development and hand over by the end of the project As I mentioned at the beginning, please consider submitting the following: 1 - Highlight any prior projects Classified Ads in Xamarin or Flutter, if any, otherwise share what you have developed in these two frameworks - Estimate for the time required for each stage and cost and for the whole project, for example: ** Apps Wireframe[$$$] -> XX weeks using ..... ** API[$$$] -> XX weeks using ..... ** Back end Apps[$$$] -> XX weeks using ..... ** Front end Apps[$$$] -> XX weeks using ..... 2- Tools that will be used for code documentation and versioning 3- Other tools or technologies(real time communication for CHAT and Notifications) that may consider as added value for the project