C# Expert for Application Development

We need a Xamaarin(C#) application for Mac and Windows Need a C# application that will allow members to partake in a specialty video [login to view URL] to develop the app from scratch and complete it as soon as possible. All technical stacks are already ready to start. Once you complete this functionality, we will need to integrate into another application and over solution components that are also Xamarin based and we need to target desktops and mobile applications in the final solution. So we want long-term working relationship.