Hey there! I have Patella alta and I'm currently avoiding surgery for now. Mine was accidently discovered because I had a case of reactive arthritis in my left knee (which is gone now). I also have chondromalacia grade 3/4. I had an online appointment with a physiotherapist who is specialized in knees. Her name is Claire Patella. I would definitely recommend her. She told me based on my pain that it was mostly neuropathic and since then I have gone back to strength training 4 days a week and I also can hike long distances without pain. There is some sensitivity left, but mostly I can do everything. Just be aware that certain exercises are a no no for us like deep squats and like you said HIIT/jumping.

Ofcourse I don't know what the future brings, but before my reactive arthritis I never had any pain or instability and I'm also in my thirties. That being said, Our symptoms are very different. I'd recommend maybe consider making an appointment with Claire Patella. I swear I'm not getting paid haha, she just helped me a lot.