I didn't have surgery, mine was hormone for 6 months, HDR Brachy and EBRT for 23 doses. It took 3 years but nocturnal erections are definitely back, in fact over last 6 months they are harder than when I was a teenager I think. They certainly wake me up and stay for half an hour or longer. I had dry orgasms for 1st year after erection returned but now I ejaculate quite a lot of clear fluid that turns very sticky quite quickly but my orgasms nearly blow my head off. Wife finds it funny as it goes on for several seconds, more like hers did.
It has taken me 4 years, but now have great sex life with my wife, maybe not as acrobatic as we were when we met in our teens, but probably just as much fun. So don't ever give up or let it beat you.
Mike