Hi there,
I'm willing to take the challenge by creating your desired app. Here the real challenge is support for older version of android which I think will be handled easily. I've already done some things like this in the past and I would be happy to create a demo app for you before even assigning the project.
More about me:
Full stack application development for more than 15 years of professional experience of corporate grade applications in technologies that include ASP.NET, JQuery UI, JavaScript, .NET Core.
Corporate-grade desktop applications for Windows in WinForms (C# and VB.NET), Electron, UWP.
Mobile applications development: Android Native (Java/Kotlin), Flutter, Xamarin and Xamarin Forms.
Experience with developing advanced apps for legacy mobile platforms: Windows CE, Windows Mobile 6.
RESTful API backends with OAuth token-based authentication and offline data synchronization.
Database design development for SQL Server, MySQL, SQLite.
UI Components: Telerik, Javascript charting libraries.
Reporting: Crystal Reports and MS Reporting Services.
Experienced in advanced signal processing applications, sensor data acquisition and processing.