Hi Brita,
It is not currently possible to select a photo from another app via the sharing capabilities. Thanks for the suggestion though, and I have created an enhancement request in our backlog for this feature. In the meantime to be able to select a photo via the browse button on an image question, it will need to be saved to your gallery first, so I would suggest using the download option from within the other app you want to access it from, then save to your gallery so that Survey123 can see it.
Phil.
