ZapVM is a free app (with some desirable in-app purchases) that lets you create and share messages with sound, still photos, captions, stickers and freehand sketching tools.
I can see ZapVM being used by PowerPoint or Keynote fans, families sharing events, for consumer reviews of places or services, vacation photos, even simple hello messages. The app does all the editing and processing right on your device, so no data link is needed until it is time to share.
I tried the app and had good success. The options can be a bit daunting, so take a couple of minutes to understand all the icons. In a nutshell, here is the process: Take a photo or get one from your camera roll. Record a narration. You can swipe through up to ten images. When you are done, use the drawing tools to annotate your presentation with things like arrows, captions, freehand drawings or text and other graphic elements. When you are done, your images and annotations get rendered into a video, which you can then share. You don't have to register to use it, you can just send your 'Zaps', as they are called, directly from the app.