It sadly isnt guaranteed 1 op piece per waves, only in high player servers, ive gotten 0 op pieces many times also the white keycard is used in interrogation too. Not sure about rebel quests
Time stamp time 0:28 is purple keycards 1:04 is blue keycards 1:24 is green keycard how to obtain it easily 2:31 how to raid green 3:30 is orange keycards 4:30 is red keycards 5:47 is white keycards note that whites are for cargo raids and interrogation.