Aseprite can do most of the heavy lifting through its lua scripting. I would probly just export the PNGs as a series, then call the rife cmd on them, then read the resulting series back in as a new file.
Noting too fancy at first. Whatever pixel art settings work best would be nice to have, but I can make a little gui for those later.
Or, if it’s easier for you, I’d probly also settle for just making a “Export gif through rife x4” button, just as a trial run.