Forget About Shortcode Buttons by By Designs & Code is a simple way to create “link buttons” in the “classic” editor a variety of styles, which can include FontAwesome icons. You can see what the button looks like as you’re editing (as opposed to having a “shortcode” that describes the button with text).
A link button is really just a hyperlink, same as you could insert using the “chain” icon in the editor. The difference is that you get to control the appearance.
I like this plugin because it is simple and just works without fuss. In edit mode, the buttons don’t shrink when they receive focus, which I’ve seen on other plugins. There are a wide variety of choices for appearance, and the icons feature is an excellent addition.
The authors promise support for the block editor is coming. Blocks has a built-in button block, that lacks icon capability.