Sending single sign in tokens using Keybaord HID for TOTP sign in

What about using map to convert to hex string?

function toHexString(bytes) {
       return bytes.map(function(byte) {
           return ('0' + (byte & 0xFF).toString(16)).slice(-2);
       }).join('');
}

console.log( toHexString(hmac.digest(E.toArrayBuffer(message))));