Exporting ed25519 private key in OpenSSH Format JavaScript

I have created an ed25519 key pair using the javascript crypto library

    import crypto from 'crypto'
    import sshpk from 'sshpk'

    const keypair = crypto.generateKeyPairSync(
      'ed25519',
      {
        modulusLength: 256,
        privateKeyEncoding: { format: 'pem', type: 'pkcs8' },
        publicKeyEncoding: { format: 'pem', type: 'spki' }
      }
    )

Now I need to save the private key in openssh format.

I have tried using the sshpk library but when I try to export my private key to ‘ssh’ format, the library exports the public key not the private key.

 var sshpkKey = sshpk.parseKey(keypair.privateKey.toString(), 'ssh-private')
 console.log(sshpkKey.toString('ssh'))

outputs

ssh-ed25519 AAAAC3NzaC1lZDI1NTE5AAAAIIodXPD2GDD5tcgCdsmktQux+tDM8yJhzX09V9yZn4Q6 (unnamed)

So I obviously have the wrong function call here “.toString(‘ssh’)”, but, I cannot for the life of me find the right call to export the private key into the following format.

-----BEGIN OPENSSH PRIVATE KEY-----
.
.
.
-----END OPENSSH PRIVATE KEY-----

Maybe I am using the wrong library all together?