Nah, the photo viewer will be easy.
There is no need to port anything existing, just write a simple program that can display a photo onto a single window. Have it resizeable to any size, and create methods to go up/down in the playlist. Have it wait X number of seconds dependent on device data, then send the command to go to the next entry in the playlist. It should also implement the Get Video Frame command, so that something could be implemented for the orbiters.
For an experienced dev, this would be about 2 days worth of work.
Once the Picture Player has been written, a Picture Plugin should also be written to pass the media stream of pictures to the relevant picture player. (Use the Game PlugIn and Player as models for this).
The relevant screens could be made in designer for the OSD, for the non-osd orbiters, etc.. after the player is functional.