Honestly you’d be surprised how many places it just works magically. I was surprised to find that Office365 users could use emojis in names for Microsoft Teams which had no problem syncing those accounts back to an on-prem Active Directory. You can use emojis to name a whole SQL database, let alone users/passwords on it.
I keep wondering if I need to figure out how to turn that off but it hasn’t caused any problems. It’s definitely sketchy looking though when you see a bunch of normal usernames and then suddenly one is just ten snowman emojis in a row.