You can totally use emojis as passwords. You can probably even make this a policy at your company.
Edit: I thought this was an obvious enough joke, but just to clear things up: Only do this if you hate your company and everyone working there.
You can add emojis to your wifi SSID. I do not recommend it for compatibility reasons, though. Your printer might not like it.
In my experience, several devices don’t display the emoji as a correct icon (instead show the rectangle “tofu”), but they still work with it.
Source: am using an emoji with some normal characters on SSID