Whew, lots of things to consider!

Given the extent of the lesions in his prostate, risk group 5 and pelvic node +, my priority would be to halt any further spread NOW. So I'd get on ADT ASAP and probably go with Orgovyx or Degarelix over Lupron.

On whether or not to start with an RP, a lot of that would depend on the overall health of his urinary tract in his prostate. As extensive as the lesions are in his prostate they may need to treat with close margins around the urethra. So it may be challenging to avoid a significant radiation dose to his prostatic urethra if he has RT with his prostate intact. If he's had any BPH issues at all I'd be cautious about RT with the prostate intact.

The other advantage of undergoing an RP first prior to RT is your MO will be able to use PSA as a very precise biomarker for residual disease in the pelvis or anywhere else. With RT they would be measuring the PSA produced by the intact prostate cells and you have to wait a period of time for the PSA to hit a nadir, so you don't get that good of an idea of residual disease for some time.

The risks of doing an RP first are well known - sexual impacts, will take a few months in most cases to regain acceptable continence, and I've read some people thinks it increases the risk of physically spreading some cancer cells during removal.

I'm not sure of the timing relative to either primary treatment method, but the standard of care since the outcomes of the STAMPEDE platform of trials is ADT intensification by adding abiraterone/zytiga to the basic ADT for at least 24 months.

Prayers and best of luck to both of you.