macos – How to find the list of usable icons in mac cli applications

I am currently developing a node application and, having used the npm tools, my interest has been drawn to the use of npm-check and its use of the icons in its cli interface. for example:

enter the description of the image here

There must be many other icons outside of the illustrated heart, but I would like to know how to access them, so I can use them in my own CLI applications.

I'm currently using macos, but I hope these icons are platform independent (?)