I do not use the WP GraphQl plugin and am unable to provide you any specific advice. Generally I would say that if you are able to access other ACF fields in this way, then it should be the same for your FontAwesome fields.
This plugin does not do anything additional beyond ‘standard’ ACF custom field functionality to provide support for WP GraphQl.
Unfortunately, WPGraphQL does not support any 3rd party extensions of ACF. https://www.wpgraphql.com/acf/
I’ve opened up a ticket with WPGraphQL for this but I’m not sure on which end the support for GraphQL needs to be added (the plugin or WPGraphQL).
https://github.com/wp-graphql/wp-graphql/issues/1847