How does the CommunityToolkit.Mvvm reduce MVVM boilerplate?

CommunityToolkit.Mvvm provides source generators. [ObservableProperty] on a partial field generates a full property with change notification; [RelayCommand] on a method generates an ICommand. ObservableObject supplies INotifyPropertyChanged. This removes most hand-written property and command code.

public partial class LoginViewModel : ObservableObject
{
    [ObservableProperty] string username;

    [RelayCommand]
    async Task LoginAsync() => await Shell.Current.GoToAsync("//home");
}