As you know, RFC 7540, which describes HTTP/2, was published recently.
I think HTTP/2 in .NET Framework is a matter that should be talked/discussed in forums.
What I’m interested in is client side.
Classes of HTTP client exist in System.Net.Http.
Browsing source code, it seems “core” implementation exists in native Windows HTTP Services (WinHTTP) API and that is called from System/Net/HttpClientHandler.CoreCLR.cs via System.Net.Http.WinHttpHandler.