Well, I would use a collection containing all the data that is linked to a gallery. If you create an item in the collection, it will show in the gallery.
On top create a text input in which you will describe your task and next to it a button (or icon) 'ADD'. Underneath create a gallery, in which you can put a label (or a text input if you want to edit it afterwards) and other controls if necessary.
When something is written in the text input and you press 'ADD', collect the task to the collection (see image). Assign the collection to the items property of the gallery.
Of course, I suppose there will be some kind of backend to this app, so you can link the collection to that or instead of the collection directly work onto the database, which is basically the same.
