It's a mapping between some keys pressed and some output. If you really need emojis, make that your output. I map A-R to "->" for C programming. You could map H

It's a mapping between some keys pressed and some output. If you really need emojis, make that your output. I map A-R to "->" for C programming. You could map HR*APHD (for "lambda") to λ if you wanted. Honestly, the bigger restriction is whether the receiving application handles Unicode. I'm only familiar with Plover steno theory. It's hard to imagine that theories would exist without a phonetic fallback (in the event that you don't know the stroke for a word). All of them will have fingerspelling. For English, there's at least Plover, Phoenix, and StenEd. Other languages have theories, too. All theories have "briefs" which are strokes assigned to something other than phonetics. Instead of writing A/TKEUGS/AL ("a", "dishn", "al") for "additional", you can stroke ALG. The STPH-P for up is another example of a non-phonetic brief. In that case, the "theory" is the shape of the key layout. Some people go crazy and just memorize a bunch of, essentially, random key-to-output mappings. I've heard that's pretty close to what Magnum is like. It's mostly brute memorization based on statistical frequencies of words and phrases and "easy to stroke" keys. That's how you get to 360 wpm.