I’m trying to use icons from Google in a theme (same icons from Daemonite theme). Anyone knows who to replicate it? I tried this: Developer’s guide to Discourse Themes
Daemonite imports the icons from Google and uses the old icon renderer to display them with CSS. Below are the key chunks of code you would need to add to a theme component of your main theme. Keep in mind you will probably need to add some additional styling beyond this.