With my commercial operator:
Tried to compose an SMS with emojis but my current SMS app doesn't seem to
support them (FP2 Open). I guess I could set signal as my SMS app...
I sent myself 40 emoticons and at least signal displays them correctly.
Then I sent 40 and quickly changed the default SMS app back to the stock
Messaging thing to receive the SMS there, and it also shows all 40 intact.
Notably displayed as emoticons, apparently it does support them after all.
~N