In order for any font to be able to render emoji or other special utf8 chars, 2 specific fonts must be installed:

pacman -S noto-fonts noto-fonts-emoji

Special note for Appy users

noto-fonts is required to display, within the UI interface (via a web browser), UTF-8 chars used to represent UML associations in UML class diagrams accessible via the Appy admin-zone (page Model).