Within PowerApps there is one control ( attachements in forms) thsat acceptsthe drag and drop of documents. This means that when you want to deliver drag and drop fucntionality in a PowerApp you would have to create a temporary list and a form that only displays the attachment field. Then trigger a flow on this attachment's list item. This is not a great UX.
Also the attachment control doesn't give you much flexibility as to the look and feel of the control.
Can we have a drag and drop control added to PowerApps?