Best answer
Yes. An emoji is just text as far as matching is concerned, so 馃敟 works as a keyword and contains mode matches a message of 馃敟馃敟馃敟.
This is genuinely useful for comment automation, because a single emoji is the lowest effort reply you can ask for. "Comment 馃敟 and I will send the link" gets more comments than asking people to type a word, and it reads as native to the platform rather than like a form.
Two practical points.
Skin tone and variant selectors matter. Some emojis have modifiers that make them different characters, so 馃憤 and 馃憤馃徑 are not the same string. If you ask for a thumbs up, use contains mode on the base emoji rather than equals, or list the variants.
Do not mix an emoji prompt with an equals trigger unless you mean it. People send three fire emojis, not one, and equals mode wants the message to be exactly one. Contains mode is almost always the right choice for emoji prompts.
Worth pairing with a tag so you can tell emoji responders apart later. They tend to be a different, more impulsive audience than the people who typed a full question, and treating them the same way in a follow-up is a missed distinction.