Just a FYI- If it really is a pre-production/engineering sample there could be legal issues for selling it. Depending on the exact situation, most earlier samples are still considered company property.
I would suggest checking out that situation before you try to sell it. In your case, it seems like it was a regular production run and possibly with a very low serial number, so potential value increase right there.
On the other hand, extremely rare pieces of hardware and or games (even Eng/Dev/Demo stuff) can sell for ridiculous amounts if you find the right collector.
The whole card/video game/box collector market entered a huge bubble during covid and I haven't really been following what has happened the last year or so.
If it is a really rare piece with high demand, getting it graded or authenticated somehow could drastically increase the price.
I would think I guy that has the hobby of documenting the history of early gaming would give you a pretty realistic idea of what it is potentially worth or at least get you in contact with someone who knows.
I would try to contact that guy at pong-story and see what he thinks.