UPDATE
I have attempted to access Google Sheets by logging directly in to Gmail or YouTube via Selenium using Google Chrome, Microsoft Edge and Mozilla Firefox. I also tried to use a side-channel Google login through Stack Overflow and other services. Only once I was able to get far enough, before I was thrown under the crazy captcha bus.
After all these failures, I decided to gave this problem more thought. I determined that you didn't need to log in to Google to access the document in Google Drive. You just need to share the Google Sheet from the account that controls the document with the permissions needed to read the sheet with Python.

Once the sheet is shared you can access and query it using Selenium.
from selenium import webdriver
from selenium.webdriver.chrome.options import Options
chrome_options = Options()
chrome_options.add_argument("start-maximized")
chrome_options.add_argument("--disable-infobars")
chrome_options.add_argument("--disable-extensions")
chrome_options.add_argument("--disable-popup-blocking")
# disable the banner "Chrome is being controlled by automated test software"
chrome_options.add_experimental_option("useAutomationExtension", False)
chrome_options.add_experimental_option("excludeSwitches", ['enable-automation'])
driver = webdriver.Chrome('/usr/local/bin/chromedriver', options=chrome_options)
driver.get('https://docs.google.com/spreadsheets/d/<google provided random string>/edit?usp=sharing')
Here is the shared Google Sheet, which didn't require a login to access or edit.

ORIGINAL POST
Google forbids using automated scripts, such as Selenium for logging into Gmail.

When you click Learn More you get this message.

Please note this line: Are being controlled through software automation rather than a human
YOU CAN BYPASS THIS, but you have to login through another portal, such as Stack OverFlow that will allow you to use your Gmail credentials to login. Once that happens you can access your Google Sheet.
If you need help with this please let me know and I will try to put some code together for you.