The only real landmine for c# is the default thread synchronization. If it was inverted, the language would be much better off. I think they also made a mistake in removing the OOTB method for throwing away the sync context, but I guess there are many third party libs that provide it.
.NET Core web apps have no synchronization context anymore, which is exactly what you're asking for if I understand you correctly. There is no need to call ConfigureAwait there.
I think this is different for GUI apps, but I have no experience with that.
