Vulcan: sorry about your Dad having to go through this stuff.

Fusion Biopsy is a good choice.
Ask your doctor to test for aggressiveness using the biopsy material: https://decipherbio.com/
Nccn.org will give you guidelines as to what to expect through different phases. It was created by DR’s for DR’s and patients.
Look at viewray.com. They make the only radiation machine in existence that combines an MRI and Photon radiation machine into one operating unit. The greater the MM in radiation treatment the greater the chance of healthy tissue issues. I had 5 radiation treatments.
Get a second opinion wherever you can. I had Gleason 3+4 restricted to the prostate and a 20.2 PSA. Keep asking questions. Its a process and coming back to this web site will help you make better decisions and provide emotional support for you and your Dad.