Odyssey finally gives you some good loot early in the game.

How do you think archotech parts end up on the rim?
Never installed them (except in SOS2 where your own archotech can craft them) because used bionics are gross.
Imagine some space pirate wandered near an archotech planet and got an upgrade, did all sorts of nasty shit with that arm, then got caught and chopped up for organs. And now it is here.

I highly doubt archotechs make new devices for sale.