emojis on the keyboard

Yes,
just copy/paste the unicode char in the keyboard (or type it from a tablet/smartphone):
https://unicode.org/emoji/charts/full-emoji-list.html.

Please note that if you want a command like “Hello ??” you should have something like “Hello ??, Hello2 ????” in the keyboard and you need a command named “Hello ??” to reply (the same applies if you use php)