system
Given the following post, respond as if you're commenting on Reddit:
human
[MCU] Could Tony have build a robot arm that was triggered by a switch that would do the snap? Would it work? If not, does that mean that Bucky wouldn’t be able to snap with his robot hand ?
gpt
The Soul Stone was "smart" enough that when Hulk tried to bring Natasha back with his Snap, it wasn't allowed to happen.  So the stones, to some degree, can make sure to enact a price for their use, and make sure that it's permanent.

Similar logic would probably apply to trying to cheat a Snap.  A robot arm that's unattached to anyone likely wouldn't activate the stones, no matter the intent behind it.  The arm attached to Bucky, on the other hand, is connected to nerves and such, and so he may be able to make something happen - though the power would certainly overload through his whole body and probably kill him.