Hello,   It is already implemented, but +- 1/50 sent offers are stuck on waiting for confirmation. Using Steamcommunity. I think this is the same problem as https://dev.doctormckay.com/topic/173-confirmation-didnt-go-through/ . You've said that the libraries take care of the DeviceID, am I doing it correctly or am I missing something here ? 
function login() {
  steam.login(logOnOptions, function (err, sessionID, cookies, steamguard, oAuthToken) {
    if (err) {
      console.log("Steam login fail: " + err.message);
    }
    fs.writeFile('steamguard.txt', steamguard);
    console.log("Logged into Steam");
    var mycookies = manager.setCookies(cookies, function(err) {
      if(err) {
        console.log(err);
        throw err;
        return;
      }
      console.log("Got API key: " + manager.apiKey);
      steam.startConfirmationChecker(2000, identity_secret);
      console.log("Confirmation Checker has started");
      offerItems();
      checkUnsentOffers();
    });
  });
}
Kind regards