What is the general goal of the feature?
To reduce tampering of the pictures attached with the forms.
What are some example use cases for this feature?
This is valid for the cases of field visits, something like quality monitoring, school inspection, etc.
The GPS co-ords pulling should be paired with the picture question by default. This is to counter the situation that a form has pictures but does not have location question. So, the picture question should have its own co-ords feature.
Most of the Android devices I've seen have a setting that allows GPS/location to be embedded in the camera image. And if your camera app doesn't support that (or your processing pipeline can't extract that data), you can add a GPS question to the form. Is there a reason why that approach wouldn't work?
Just saw a suggestion at ODK Best Practices - #8 by jniles that might be useful.
For additional audit-ability, use OpenCamera with a custom text, timestamp, and gps stamp embedded into the photo. For those stuck on older Collect versions, it also compresses photos to reduce bandwidth.
Our approach to this is to make it possible to specify a custom camera app to use in a form definition. The user will need to have that camera app installed and correctly configured. The values collected by the camera app will not be saved to the form definition.
More at Using a camera app other than the default one in Android 11+