Maybe by the time when you asked that, Linux didn't able to do it so easily, but, at least in ubuntu you can simply paste an emoji and it will appear in the prompt:

PS1="\[\033[1;33m\]\[\033[0;44m\] \W 📅 \d \$ \[\033[0m\]\[\033[1;32m\]

although, i don't know whether this way for adding an emoji is valid.