Hi Diego,
Just to share my last research..:
The fastest method to use icons is SVG Inline, but it is not the easiest !
so,
* For using classic social icons into GP theme you can use this one (it seems you can also add custom svg icons with this plugin): https://wordpress.org/plugins/gp-social-share-svg/
* For custom svg icon anywhere, you need to “build” or to copy the <svg> inline code from Icons you need (from website/adobe/icon dedicated website suppliers) into a html bloc.
What I did to “simply” reuse svg inline is:
* Build a CPT custom post type called Icon
* Add a post per Icon
* Add thesvg inline code in a field
* Then you can call it using shortcode – get_field() function or/and you can use relationned field of ACF plugin
good luck =)
I’m novice, so wait for David he probably has a better idea !! 😀