I get some occasional hip impingement due to a couple years of heavy wide stance low bar squatting. High bar and front squat feel perfectly fine which is why I'm assuming it was the low bar that did it, it built up into some considerable discomfort that never went away. RDLs, stiff leg deads, sissy squats, leg extensions (Properly), weighted pushes/pulling, and weighted climbs should be easy on the hip.
In any which case, what personally feels comfortable to me are sumo deads with more of a squat stance since it loads on the posterior chain first and I don't get discomfort while still working the quads some. Light Bulgarian split squats and lunges also feel perfectly fine as well as step ups. Another option may be heavy sled pulls or pushes. Really though the right answer is to work something out with the sports doc. If your hip is legitamtely shot sometimes there isn't an option and you have to think of health over exercise. My dad was in the spot at your age with his shoulder and he kept poking around for alternatives when he should have listened to the sports doc. By time he did eventually get his shoulder replaced he had to go to a number of different surgeons before he could find one that would operate because there were so many bone spurs and not enough joint left to work with in the first place. Now he's at the point where he listens but it took the surgeon explaining that he won't get another replacement and if it collapses he's looking at amputation.
Get a second opinion from another sports doc but if it is truly that bad I'd say it might be best to switch to the mentality of exercise for mobility and joint health and put strength/performance of your lower body on the backburner.