Suddenly, Alpine is asking me for a master password to unlock the password file. And then after I defined one, it did not work, though to be fair maybe I mistyped it and that password was not what I thought it was.
And in a terminal, went to
and issued the following command, as instructed:
$ openssl req -x509 -newkey rsa:4096 -keyout MasterPassword.key -out MasterPassword.crt -days 10000 -nodes
Then ran Alpine and did as was told, including going into (S)etup Co(L)lections and added /novalidate-cert to the end of the imap.gmail.com line.
And that seemed to work pretty well.