I'm using Feature Flags as described here. It works alright, I'm just wondering if the following is really the best way to use them if I want to switch between different service implementations inside ConfigureServices()?

I have the following so far:

using Microsoft.FeatureManagement;

public void ConfigureServices(IServiceCollection services)
{
    services.AddFeatureManagement();

    var sp = services.BuildServiceProvider();
    var featureManager = sp.GetService<IFeatureManager>();

    if (featureManager.IsEnabledAsync("UseServiceB").Result)
    {
        services.AddHostedService<MyServiceB>();
    }
    else
    {
        services.AddHostedService<MyServiceA>();
    }
}

Especially since IFeatureManager only provides an async method to check for a feature, this doesn't feel quite right?!