Emoji were in widespread use in Japan on the mobile phones of the generation before the smartphone. That is a corpus of many years of human communication which falls within the goals of Unicode to unlock. Those emoji may have been invented by AU, Softbank, and NTTDocomo, but they exist.

The recent additions come from a variety of proposals; most seem to be independent initiatives.

Big tech embraced emoji, but they got in the standard without them. Their widespread use was pretty much a given.