I lost my phone just this week, and in setting up another device, I noticed that I was able to authenticate using the Google app in yet another (signed-in) devi

I lost my phone just this week, and in setting up another device, I noticed that I was able to authenticate using the Google app in yet another (signed-in) device that was not connected to the internet, a la 2FA authenticator code apps. I'm not sure how recent this authentication mode was introduced, or if it's available only in select situations, but it would have completely resolved the librarian's complaint.