I really enjoy the story missions but appreciate that there is little challenge to them once you hit cap. How about the opportunity to make a nightfall game card system for story missions? Doesn’t need connecting to a timer like nightfall but opportunity to increase the difficulty
Similarly the rewards could be graded according to the difficulty
Do mission solo gets better reward than as a fire team, doing it with a higher level of difficulty further increases the quality of the reward (gold, silver or bronze in d1 speak).
Just a suggestion.