Hi David, many thanks for the quick reply.
I've now made some progress, but I think I may have misunderstood some of the core concepts here.
Firstly, I cannot figure out where the following code in your original post is meant to be placed (unless it is hidden somewhere, or something that powerapps quietly runs in the background without the user needing to be aware):
Circle1.X = ThisItem.x-ThisItem.radius
Circle1.Y = ThisItem.y-ThisItem.radius-ThisItem.index*Gallery1.TemplateHeight
Circle1.Width = ThisItem.radius*2
Circle1.Height = ThisItem.radius*2
Circle1.Fill = ThisItem.color
Secondly, I tried to bind my data directly to the gallery as you described. Unfortunately, no available data fields appear on the right hand pane, even though I changed the fields to x, y and radius as you suggested.
Finally, I am confused by the term 'Gallery1.Items = CollectionSample'. Surely Gallery1.Items=Fruit (since this is the table which is the data source). Unless you are refering to the approach of using a collection rather than an external data source, as per your demo?
I apologise for any fundamental misunderstandings here; I am doing my best to get a grasp of what's going on! I have done my best to follow your guidance to the letter, and would really appreciate any help.
Thanks anyway for the guidance provided so far 🙂