I don't really know if you are using Android or iPhone but I m more sure for Android, if using chrome browser in Android go to settings then password, enter the phone password to reveal the saved passwords to get your Google password since you said you used your google to signup betnomi account. After you reveal it copy out the password and paste to your betnomi where they asked you of your password to activate 2FA.
I have both an Android phone and an iPhone, but I used my PC for stuffs and this too, but what you're suggesting wouldn't work, I know my Google account password but that's not the way it works when you signup with Google plugin on website, Google doesn't send your goggle account password to the site you're registering on, I don't even think they create a new password on your behalf for the website, what they use is some cookie and web application sessions and stuff like that.