I think this falls under a feature request. When I go Location Rules -> Page Parent, it would be nice if the list would also populate with any custom post types that are hierarchical, not just pages. We use hierarchy in a lot of our CPTs, and often I want to use a custom field based on the hierarchy. This location rule would save me a ton of time.
This can be solved by adding custom locations rules https://www.advancedcustomfields.com/resources/custom-location-rules/. This is an easy one because you can basically copy the page parent rule function and make a couple of changes to get it working.