A Linux tool to authenticate a Gmail user with Google OAUTH service.
No need to go to Google console. No client_id or client_secret required.
Opens default browser to ask user permission. Requires xdg-open command.
Granting permission you will see warning about not verified client.
Just continue. It takes making a YouTube clip to verify. Not for me.
Keeps tokens under user's local ~/.mutt/accounts folder ONLY.

To build run the sequence

git clone git@github.com:Kontra2B/OAUTH-login
make -C OAUTH-login
make -C OAUTH-login install

Installs to ~/.local/bin that should be in $PATH. Otherwise you need full path to oauth.login.

Can be run standalone oauth.login your.user.nick@gmail.com or with an e-mail client.

Tested with MUTT. An e-mail text client.
You need the following settings added to your .muttrc:

set imap_user = "your.user.nick@gmail.com"
set imap_authenticators = "oauthbearer:xoauth2"
set imap_oauth_refresh_command = "oauth.login ${imap_user} 2>/dev/null"
set smtp_authenticators = "oauthbearer:xoauth2"
set smtp_oauth_refresh_command = "oauth.login ${imap_user} 2>/dev/null"

Remove imap_pass and smtp_pass from .muttrc.