Consultation is done by doctors and lawyers. The internet is full of anecdotal evidence and general BS so you get what you get when you ask this question in public forums.
The link below is pretty a pretty good summary although you will be able to find many differing versions from well known institutions and industry publications:
https://www.pcf.org/sexual-health-changes/erectiledysfunction/Removing or destroying a sexual organ cannot possibly result in one's sexual life being exactly the same afterwards. Expectations have to be tempered with the reality of the situation.
You are young which is good for recovery. However, you stated that you already have some ED issues, probably as a result of prostate issues, so it is not prudent to expect that to get better from prostate cancer treatment(s).
I think it would be a good idea to include your partner in some of your doctor visits and have some frank conversations about
your PCa. Beating cancer usually comes first so keep focused on that and tend to the family issues when appropriate. I always regret not going to my wife's BCa doctor visits due to work & travel conflicts at the time (around 50 yo) but did what I could to help through treatments and home life. She did a better job helping me with PCa.