My non-professional take is that likely, since the ruck is up on your back you will get more benefit all over. Ankle weights for me have been for work on the floor to increase the load when I do lifts. I am not an exercise professional, rather, I would do some Googling on that. Any time you add weigjht to the END of a limb, you put greater pressure on the joint, such as the hip or ankle. Rucking works the entire body for endurance and cardio. Again, not a PT or doctor, please consult a pro for that input, or reach out to Jenny Brown (her comment is above) who is in that business.