My Android (Google) camera app has a function where photos can have an embedded ~2 second video in them, to create a MVIMG file. The Google Photos app allows viewing of the looping video, similar to a gif. It also allows extraction of a single frame to pick the best moment.

I'm not sure if it's beyond the scope of Simple Gallery, but it would be great if it could support this format. (At the moment, it's the only thing preventing me from uninstalling Google Photos.)