Unsure if this is actually possible as when you create a page item, you need to associate it to a specific region, which is not what you are after. I am unsure how many pages you are talking about here but in order to avoid the use of a region in every page, you could actually create application items within "Shared Components" for the pages you require a page item for, which wouldn't require a region for these but you will need to ensure you manage each of these new application items for the relevant pages.
For example, if your app only has 5 pages alone, you would create 5 separate application items, i.e.:
and then for instance, you would use say :AI_P5_ITEM within your page 5 only and so forth, for the others.
Unsure if this will help but hopefully might be another workaround.