Although I really adore the idea, I'm in doubt whether adding another offsite dependency is what we should aim for. Downtime of this service might affect all Flarum installations, which - at least to me - sounds like a huge risk.
Also please note that beta 8 already moved towards icon pack interchangeability by demanding all icons to use the full icon class fas fa-heart instead of heart. This by itself allows you to use any custom icon you'd like in Flarum where the icon class is configurable (eg for permission groups).
Seems like I voiced this over a year but we never , perhaps one of you is willing to open an issue discussing interchangeable icons?
