The other option, per a couple sites like:

https://gist.github.com/bnagy/8914f712f689cc01c267

I set up application passwords, then configure a gmail rc file ~/.muttrc.gmail with the important bits:

  source "gpg -d ~/.pass/gmail-mutt.asc|"
  set from="ME@gmail.com"
  set spoolfile="imaps://imap.gmail.com/INBOX"
  set folder="imaps://imap.gmail.com/"
  set postponed="imaps://imap.gmail.com/[Gmail]/Drafts"

and the GPG encrypted file has the following:

  set imap_user="ME"
  set imap_pass="APP_PASSWORD"
  set imap_idle="yes"
  set smtp_url="smtps://ME@gmail.com:APP_PASSWORD@smtp.gmail.com:465/'

I wrapped a simple gmail command to run: mutt -F ~/.muttrc.gmail

GPG pops up a password prompt, then mutt does it's thing and works just fine.