From a quick look at the source [0], it looks like it supports Mono. I can't see anything stopping it being ported to Core, apart from JonSkeet.MiscUtil may not support Core.
If you package this up as a NuGet package and support Core then can you please ping me and I'll add it to https://anclafs.com.
I've been prototyping a .NET Core port. JonSkeet.MiscUtil source code is fine for Core, but for the BitTorrent code we need to change the HttpWebRequest objects to HttpClient and rewrite the Begin/End/IAsyncResult/callback-style to async/await.