Yes Friday is a Government and Public holiday in Maldives ,including Banks and other big companies ,but it is not a holiday for small shops and ferry service to the Airport and Mainland Male'. Only that during the afternoon prayer time as people will be in the Mosque for the Friday prayers hence the ferry frequency will be less and you may have to wait ,else it is available daily. You can either avail the common airport service for people going to catch the flight or returning to Maldives from abroad or take a private ferry for yourself but you pay more for a private ferry. Hope it is clear. Best of Luck