How to login with Fido U2F secured Gmail account in Android phone? Gmail App password generator's code, the one of 16 character length, does not work.
There are no other options in the password page than Create a new account. 
The password page does not accept my password which works in my Gmail account in PC. 
I set up the phone first time without Gmail account. 
So I am now in the password page where you can go many ways


Settings > Accounts > Add account > Personal (IMAP) > [password page here]. 
PlayStore > [same password page here].


Phone: Oneplus 3 T
Android: 7.1.1
Fido U2F Security key: YubiKey Neo
Answer from Oneplus support chat


  Unfortunately, there is no option for that right now. You will need to use another gmail account without YubiKey so you can install the applications that you want to yur OnePlus 3T.


Me requesting a plan when the feature will be implemented


  I will take note on that information and forward that to our ROM Team and hopefully, it will be available in the future.


I required them to inform me about the implementation but they could not offer a strict schedule. 

Whatsapp's support answer

Confirmation that Oneplus Google Drive backup is not supported in Oneplus by WhatsApp


  Hi,
  
  Thanks for your message.
  
  The user cannot directly access data in the hidden app folders, only
  the app can access them. WhatsApp data is on a hidden folder in your
  Google Drive. To check whether or not your backup file is saved in
  Google Drive:
  
  Go to Google Drive (https://drive.google.com) and log in to your
  Google account. If you are accessing the link from your phone, you
  have to tap the [Menu Button] in the top left corner and then choose
  to use [Desktop Version]. Click on the [Gear] icon in the top right >
  [Settings] > [Manage Apps]. Scroll until you find WhatsApp in the
  list. Please note it may take several minutes for WhatsApp to appear
  in the list. Additionally, you can wait until “Hidden app data” size
  appears if you wish to see your WhatsApp backup size. Note: This may
  take several minutes. Learn more about Google Drive backup in this FAQ
  article.
  
  Note: If you wish to read your chat history on your computer, please
  use our Email chat feature instead.
  
  Thank you for your understanding and cooperation.
  
  Regards
  ...
  WhatsApp Support Team


Output: you cannot access the data directly, only see the size of the backup file.