Great question and a popular use case. You can definitely create a submit action. There are two ways you can approach this, through an import action or with a Boolean line item with DCA.
With an import action, you will set up the saved view to import the approved information to a "staging" module that holds all the approved values from the region heads.
With a Boolean, you will allow the region heads to click the checkbox indicated approval. Once checked it will become disabled and so will the ability to change any of their planned values because you used DCA on it. You'll also need to create a reset action to make the plans editable again once the planning cycle has ended.