Yeah this is dead tech even if someone wanted to reproduce and re manufacture boards like Naomi or Atomiswave or anything that's not off the shelf parts is basically impossible or a complete waste of money.
These processors alone are custom fabricated and even if you got the designs and rights to make them, good luck having volume high enough to have a chip manufacture run a line to make the silicon dies and stuff. Its much like the way of the CRT its lost to the ages, designers die or retire and forget. You need large volume to make it remotely economically viable and affordable.
Any who,
These are probably old stock from manufacturing reserves. Who knows if any of them are DOA from the manufacturer eons ago though. Still pretty cool to even see old stock like this floating around.
As someone mentioned
@sheep_nova is a trust worthy person cant go wrong there. I know plenty of friends that bought from them.
If this seller cant test these boards ahead of time for you or at least maybe offer assistance,exchange, or return if its dead (I mean they are unused right). Then I would pass on his offering even if it is clean.
Good luck getting your Atomiswave its got some pretty fun games on it