MVP capable of development into full-stack mobile, desktop and backoffice application

This is not necessarily something that can be done on this site, so consider it a 'reach-out' to see if Freelancer.com is an option for us: We have a project, with good backing, that needs a mobile app (Android and IOS) with some desktop functions as a web app. It needs, under the bonnet, to be a well-architected, secure and highly scalable application that follows best practice and can develop and extend rapidly. We expect it to be in the order of between 50 and 150 man-days of work over a three-month period, with the initial focus on a Minimum Viable Product which is about half of the work. What makes this tricky is that we do not have time for teams to form, set up standards, tooling and methods. So we also have to find a supplier who already has: - An established team used to working together on an established toolset - An established (agile) methodology in place and well-used - Ready-to-go and proven environments covering code control, testing (including automation), deployment channels, QA and so on. Best practice that allows for the app to develop continuously into the future - ideally with releases every two weeks or less. - A library of re-usable elements that can cover the elements of our requirement which are standard or common, e.g. account registration/verification and admin. I realise that this is not necessarily cheap or easily done - but if you are connected with some kind of organisation that can deliver the above and can show that you have been doing so for some time (we do not have time for learning curves!) then please get in touch. We don't need you to spend time at this stage - just to make contact with an outline of how you think you can go about this. The nature of the project itself is under NDA so apologies for vagueness there. Suffice to say there is nothing technically unusual in there - just variants of functions you'll have seen in other apps.