ProGet's Universal Packages and Feeds certainly support full SemVer2.
If you're designing modern delivery processes but are still planning to shoehorn your applications into NuGet packages (i.e. meant for .NET DLLs), you really ought to consider fixing that as well. We also released Romp which extends universal packages, and gives some nice deployment options as well.
That being said, NuGet feeds and packages have whole lot of quirks (e.g. 0.01.0 != 0.1.0, etc) that make SemVer2 nearly impossible to implement without some major breaking changes. NuGet.org had a lot of problems too when the quasi-supported it in the client. So we're planning on making those changes in ProGet v5, which is scheduled for November.