I managed to configure UserSecret in a console app where I basically replace App by Program, but it seems that the following (simplified) code does not seem to work with a WPF app.

public static IHostBuilder AddServices(this IHostBuilder host)
{
    host.ConfigureServices((context, services) =>
    {
        var builder = new ConfigurationBuilder()
            .AddUserSecrets<App>() // I don't know if it is 'App' to use as the generic.
            .Build();

        var config = builder.GetSection(nameof(UserSecretModel));

        services.Configure<UserSecretModel>(config);
    });
    
    return host;
}

Can someone share his insights?