The Null Composure gambit ornament quest appears to be only tracking one type of progression - match completions. Despite what it says, it does not track targets defeated with fusion rifles, rapidly defeated, or defeated with solar weapons. I am mot earning bonus progress for defeating guardians or being on a win streak. I have done and won 3 Gambit games. It says 3% on Drifter’s winnings despite testing Jotünn and Null Composure. It would appear that it Drifter’s Winnings only tracks Gambit matches completed, which means I would need to do 100 games of Gambit to get the ornament.