ecc_pk.cs

// download https://drive.google.com/file/d/1kXYcIkDMX25km5YtSBfFa9Xxx2dx8cNB/view?usp=sharing locally

using System;
using System.IO;
using System.Security.Cryptography.X509Certificates;

namespace EccSigNet5
{
    static class Program
    {
        static void Main()
        {
            var cert = new X509Certificate2(File.ReadAllBytes("<path to the downloaded certificate>"));
            Console.WriteLine(cert.PublicKey.Key);
        }
    }
}

// Unhandled exception. System.NotSupportedException: The certificate key algorithm is not supported.
//    at System.Security.Cryptography.X509Certificates.PublicKey.get_Key()
//    at EccSigNet5.Program.Main() in C:\WLCR\github\EccSig\EccSigNet5\Program.cs:line 12

The exception is thrown here https://referencesource.microsoft.com/#System/security/system/security/cryptography/x509/x509certificate2.cs,111