My concern with allowing all apps access to ~/.cache/QtLocation is that it would be possible for an untrusted app to collect cached map data without the user's knowledge and send it off somewhere, which is why we don't share other caches (such as oxide's web cache). It would probably be ok to have an out of process trusted helper give access to/display these files in some way such that when an app contacted the trusted helper, it would display a trust prompt allowing access to shared location data.
My concern with allowing all apps access to ~/.cache/QtLocation is that it would be possible for an untrusted app to collect cached map data without the user's knowledge and send it off somewhere, which is why we don't share other caches (such as oxide's web cache). It would probably be ok to have an out of process trusted helper give access to/display these files in some way such that when an app contacted the trusted helper, it would display a trust prompt allowing access to shared location data.