Supplement question

My dad just got a “clear” diagnosis that his prostate cancer is gone. He’s on Orgovyx. His doc told him he’ll need to be on it for at least 3 more years. The common side effects I’ve read here match him, fatigue, insomnia, weakness etc. The big thing was bone density. His thinking was well I’ll be on this for 3 more years and my bones are gonna be all weak and brittle—what’s the point. Anyone have any good supplement recs? Fatigue and bone density are a main thing I’d like. Everyone says “take calcium,” but I can’t find any good recommendations for brands :( Any help would be great as he really doesn’t want to take it for 3 years if he’s gonna feel like crap.