As for established treatment for stage 4 (curative rather than palliative intent), I think that's finally starting to emerge. My situation was similar to yours on the cancer side, but without the cardiac complications — stage 4b, metastasis to thoracic spine, relatively young (56 at the time). Here's how I was treated at a major Canadian teaching hospital and cancer centre:

1. Emergency debulking surgery to relieve the pressure on the spinal cord at T3 (I was paralysed from the ribs down at that point).
2. Started on ADT (Firmagon at the time; Orgovyx now), and ARSI (Erleada) a few days afterwards and will continue indefinitely.
3. 20 gy of SBRT radiation to the surgery site 4 weeks after surgery, to kill any cancer the surgery couldn't get at.
4. Extensive rehab to learn to sit up in a wheelchair, then stand holding onto bars, etc. first in the hospital, then in a specialised rehab centre attached. (It was 3 1/2 months before I went home in a wheelchair).
5. 60 gy of SBRT radiation (curative dose) to the prostate itself 6 months after the surgery.
6. Extensive blood work every 3 months for monitoring.

If I'd had many metastases rather than just one, then perhaps I would have received chemo rather than radiation to the metastasis as part of the "triple treatment" that seems to be becoming best practice for stage 4 PCa.

Did it work? I won't know until the time (if any) that it stops working, but when fall arrives I'll be 3 years with undetectable PSA, and I can walk over 14,000 steps in a day now, so it seems to have served me well enough so far.

And I do realise how incredibly lucky I am to have been born somewhere where all of this was covered by provincial healthcare — my only expense was snacks from the hospital vending machine.