Automate moving the Instagram username from the First Name field to a custom field in workflows

I would like an action to be available in Instagram workflows to automatically copy the value of the First Name field (which contains the Instagram username) to a custom field (e.g., Instagram Username) and clear the First Name field. This is necessary to avoid creating duplicate contacts when the user then fills out a form with their real first name, as the system cannot merge contacts if the First Name field is already filled in with the IG username.