If I'm not mistaken what you describe is pretty much exactly the approach in .NET app development (WPF, MAUI, ...) with C# for the logic and XAML for declarativ

If I'm not mistaken what you describe is pretty much exactly the approach in .NET app development (WPF, MAUI, ...) with C# for the logic and XAML for declarative UI including Binding and it works well and performantly so.