Unitronics' Expander for the Atari 2600 VCS and more?

[MattyXB]

Wow, you ever heared from the Atari 2600 VCS Unitronics' Expander? Or the Entex Piggyback & the Graduate/My First Computer? All hardware for the Atari 2600 VCS, but never released.
They have only a picture from this Unitronics' Expander:


Found on a german webseite about 8-Bit Videogames, scroll a bit down, but only short text from the other Atari hardware, that they were never released:
The Dot Eaters

On 8-Bit Museum is more. But all german.

Is maybe one from them released in some way (Prototypes)? Or only this one pictures? Was there a Prototype from Unitronics' Expander, or were is the picture from?

[ragtime_tgs]

kein plan,junge

[slapdash]

I don't think anyone knows if they were prototypes or just mockups. As far as I know, neither the Unitronics nor Entex add-ons have shown up.