TarArchive.SaveXzCompressed

public void SaveXzCompressed(Stream output, TarFormat? format = default, 
    XzArchiveSettings settings = null)

using (FileStream result = File.OpenWrite("result.tar.xz"))
{
    using (FileStream source = File.Open("data.bin", FileMode.Open, FileAccess.Read))
    {
        using (var archive = new TarArchive())
        {
            archive.CreateEntry("entry.bin", source);
            archive.SaveXzCompressed(result);
        }
    }
}

public void SaveXzCompressed(string path, TarFormat? format = default, 
    XzArchiveSettings settings = null)

using (FileStream source = File.Open("data.bin", FileMode.Open, FileAccess.Read))
{
    using (var archive = new TarArchive())
    {
        archive.CreateEntry("entry.bin", source);
        archive.SaveXzCompressed("result.tar.xz");
    }
}