Further info on emojis in canned messages....
BE CAREFUL!
If you save an unsupported emoji to a canned message, all text after the unsupported emoji is DELETED. It seems to corrupt the canned message.
SUGGESTION: I always keep a backup of all my canned messages in one giant Google doc. I've been burned. If you want to experiment with emojis, make sure your messages are backed up. (Always a good idea regardless.) Try adding an emoji to your canned message. Save it. Close it. And then reopen it. If the emoji is still there, it's supported. If the emoji is gone (along with any text after it), the emoji is not supported.
FINAL NOTE: All emojis appear to work in canned message titles (which guests do not see). I use emojis in my canned message title to make them very quickly identifiable to myself. My restaurant recommendations message has a food emoji in the title. My nail salon recommendation message has the manicure emoji in the title. My massage salon message has a "hands" emoji in the title. Again, guests don't see these. But it helps me navigate my large list of canned messages quickly.
Emojis in canned message *TITLES*