https://github.com/gitgitgadget/gitgitgadget/wiki/ReplyToThis has a command that puts a password in the command line:

curl -g --user "<email>:<password>" --url "imaps://imap.gmail.com/INBOX" -T /path/to/raw.txt

https://www.netmeister.org/blog/passing-passwords.html has a decent overview of the security issues with that.

Since this is interactive, this looks like the easiest alternative: https://curl.se/docs/manpage.html#-u

If you simply specify the username, curl prompts for a password.