Approx. 6 years ago, I had a rectangular pet toy that was pretty big (maybe 6*3*11cm?). It was a puppy but there were other options. There were a couple games, one was a puzzle one, another was fishing I think? It also had magnetic contacts to connect other units. It had a touch screen. Could...
I'm not sure if this would satisfy all the doubters, but you could take a picture of your tama everyday, one picture of the date/time screen and one of your tama's age?
I hoped this helped, sorry if it didn't.