Hi @adamfaux
Thanks for the post.
This issue has been passed on to the plugin author as a feature request.
To create this field type on your own, you would need to begin by downloading the starter kit available here: https://github.com/elliotcondon/acf-field-type-template
You can then follow the step to step guide that is available here:https://www.advancedcustomfields.com/resources/creating-a-new-field-type/
I hope this info helps.