Borderlands: The Pre-Sequel had Steam trading card support added on 21 October 2014. There are 6 cards in the series, and you will receive 3 cards at random for purchasing and playing the game.
Other entries in the series, Borderlands 2 and Borderlands 3 also have trading card support.
Trading Cards
Foil Cards
Badges
Booster Pack
Emoticons
Profile Backgrounds