I have a throw-away Gmail account for forums, etc. I barely ever log into it since I have my main Gmail account retrieve emails from it over POP3.

Now, I would like to log in and Google is refusing to let me in despite entering a 100% correct password straight from the password manager.

I don't have any info except the login, the password, and, you know, the entire contents of the inbox. The POP3 retrieval continues to work flawlessly. I even get the "Someone has your password" emails. Thanks for letting me know, Google.

Google does offer some recovery options.

First is to send a text to an associated phone number but the account was created before number registration became compulsory in my country and I had a whole bunch of throw away phone numbers which expired when the law came into effect.

Second is to answer a security question but I just assumed it was for recovering the password which I did not plan to lose so I chose frequent flyer card number and probably entered a bunch of random numbers. (I know, I should have saved the answer along with the password.)

Third is to answer a question of when the accounts was created. Easy since I have the original welcome to Gmail emails. Then it asks for an alternate email address, verifies it with a code, and refuses to let me in.

So… How can I recover Gmail accounts that I already have almost full access to?

EDIT: It's not a duplicate because I didn't forget the username, or the password, or anything else. I have all the info and tried the regular recovery steps.