How does Conestoga work?
There's an official answer in the Bang! Dodge City FAQ:

Q11. How Conestoga and Rag Time work?
A. Just read the symbols. They both allow you to draw a card (from the hand of among “in play” cards) from any one player, regardless of the distance.

Adding this to the base rules of Bang! regarding the &quot;draw!&quot; symbol:

Draw a card. If “any player” is specified (see that symbol), then you
can draw a random card from his hand, or you can choose one in play in
front of him. If no player is specified, draw the top card of the
deck. In any case, cards drawn are added to your hand.

EDIT: making an assumption about a potential typo in the Dodge City FAQ.
The wording from the FAQ is a bit iffy, so it might be possible the intended interpretation is &quot;from the hand or among 'in play cards'&quot;.  If this is, in fact the case, Conestoga can be read as:
Take a card from any opponent at random, or take one at your discretion from the &quot;in play&quot; cards in front of any opponent.