I mean, what are we talking here? Using emojis with the literal translation (ie, smiley face = smiley, light bulb = light bulb) or a rough translation (ie, sun - day, moon = night), or as a coded cipher (ie, padlock telephone = encrypt all comms traffic)? Coded cipher would offer the most robust use as you could literally write a new language based off the wide range of character sets, and you could make the cipher as complex as needed. Because it's encrypted communication, it could potentially be transmitted over open channels. Of course, it's still susceptible of pattern recognition, based on the input patterns and likely output. The other two would be useless as a means of cryptography, so it would just be an ordinary hard copy document or transmit over red line. It's doable... I mean, anything is doable if you put your mind to it.

If I haven't, I'm about to.

Could not, CPT Jack Durish!
However, this reminds me of "the Anguish Languish, an ersatz language constructed from English language words. It was created by Howard L. Chace, who collected his stories and poems in the book "Anguish Languish" (Prentice-Hall, 1956). It is not really a language but rather a homophonic transformation created as a work of humor. Example: 'Mural: Yonder nor sorghum stenches shut ladle gulls stopper torque wet strainers.' This means: Moral: Under no circumstances should little girls stop to talk with strangers."
It's hilarious and our all time family favorite was Slipping Booty!
LTC Stephen F.