What would that process be?
Ummmm, well, I’m gonna have to dig out my old notes on that. Give me a bit to find them!
Bottom line, once you figure out how to make Thunderbird and/or Outlook do what you want them to do, it's just a matter of saving the webpages that helped you and any passwords you need to create. Good luck, and let me know if any of these help.
Outlook and 2-Step Verification for Gmail accounts
Accessing gmail from Outlook 2019, POP3 account, as a “secure” application
Authentication: Enabling Modern Auth (OAuth2)
Support for Google OAUTH in Outlook for Windows
P.S. I'm glad I keep these kinds of things saved!