The monogram complication is currently only available on the Color clock face, and it's meant to put your initials right on the front of your Apple Watch. But that doesn't mean you can only use your initials. The truth is, you can set the monogram complication to show any one to four (1-4) characters of your choosing. And while that doesn't include emoji, it does include the  Apple symbol!

How to change the monogram complication on your Apple Watch