hi @Alessandro.ferrarese 
welcome to the community! it is a little hard to understand your problem here so could you maybe explain with a screen shot or a video? As I understood, you want to use an input field to add items to a list and clear the input after each save then use a button to move to the next screen. But why should this button have anything to do with saving items? and why shouldn’t you save them individually?
is this close to what you are trying to do?
:raised_hand