That's cool!
We were doing similar things ourselves with GPG. But ultimately we'd forget the exact command, or the copy-pasting in then out of Slack was enough of a barrier that we'd basically never bother.
Curious how such a small barrier was a blocker. Our hypothesis is that, if we can make `fk secret send` easier than literally everything else, people will default to it, and it'll be a win for security. We shall see!