Good afternoon.
Many thanks to everyone for the discussion!
We were at the antique dealer today. He said that this eagle was indeed from the era of Napoleon!
The antiquarian is sure of this, as he has already met similar artifacts.
The eagle is gilded and, most likely, is a decorative element from a watch (watch case) or a cover element from an inkwell for writing.
He also said that with a very high probability the thing was made in a single copy for someone to order and there are no more analogues.