The help of the text node says, that Material Design Icons and Font Awesome Icons are available in the Text Node.
I can use Font Awesome icons like this: <i class="fa fa-car"></i>
How can I use Material Design Icons?
Hmm yes - docs slightly over optimistic. We use the angular-material-icons that make them available as angular directives which we use for the button, switch etc. I can't sem to see how they can be ligature style. We can either correct the info and remove from the text widget ... 
- or add them as an external web font but that would require the browser to have access to the internet.
