I use two now, Quassel which is an IRC client, and QtPass which is a password manager. Both are cross-platform which is great because I don't use just Mac. I use pretty much everything. Mac, Windows, Linux, FreeBSD.
That means most of the built-in facilities of the Mac (like iCloud Keychain) are no good for me. Because they only work on Apple OSes.
But anyway both these apps don't support this. When I press the keystroke, nothing happens. I suppose it only works for apps that use the native text input boxes, or that have built specific support for the feature like browsers.
In my password manager I can do without Emoji, though it allows for text comments and it would be handy there. In IRC it's quite handy to have the option these days.