Hi Lisa,
Phonto is a free app available for Android and iOS. It allows for text to be added to pictures that are stored in the device photo library. We have been using it for some of our aphasia clients. After the pictures are annotated, we work with the client to store them in appropriate folders in the photo library. The client is then taught to access the annotated pictures to support conversation on relevant topics. The communication partner can use the annotations to gain more information about the topic and possibly ask the person with aphasia questions, etc. to expand the conversation. This is working well for clients who don't want a speech output app but can benefit from visual scene type support for conversation.
Good luck with your project. I will be anxious to see all of the information you have collected.
Best,
Pam