I think the closest thing to that is the Draco*, which was mainly made for video tasks. Then you also have two projects being worked on currently, which is basically a a500 clone in very small factor with chipset, cpu and everything in one single chip.
There was also a a1200 clone that was of the size of a floppy disk station, but sadly only a very limited number of these were produced.
Edit: It was of course the Draco.. Thanks for pointing that out