I don't have problems with prostate, so I don't need any herb or drug, but I want to warn all here about the risks of taking something that affects ED, since we are all here for this exact problem.
I don't have problem to link the sources:
https://bpspubs.onlinelibrary.wiley.com/doi/10.1111/bcp.15129
but you should start to link the sources as well. Lots (not all) of what you suggest doesn't have scientific sources.
Serenoa Repens works in a similar way to finasteride. The former is natural and the latter is chemical, but the fact that it's natural doesn't mean it's healthy of course. They are prescribed for the same problem (benign prostatic hyperplasia), and it was found out that they also help in regain hair (for the same reason, they block conversion of T into DHT), so it's also "natural" that they share similar side effects. What's "helping" is that finasteride (and dutasteride) are way stronger in both effects and side effects, but this doesn't mean that Serenoa Repens is free of side effects. Scientific studies of SR and Finasteride/Dutasteride in long term are not so "thorough", they studied it only recently. Studies are still ongoing for side effects (and how to reverse those as well), with recent reviews. Until 10/15 years ago, SR/Finasteride were considered safe because their use were for older men, so nobody ever investigated the sexual part. Then they were approved for hair treatment in young men, and all thought that side effects were reversible, upon discontinuation. But LOTS of new-born forum regarding permanent post-finasteride-syndrome (where young men were unable to have libido/sex drive and erections back) brought the scientific community to study more deeply the side effects in young men after long term assumption. There are also lots of interferecens in these studies. Hair treatment is a giant business and pharmaceutical companies don't want to lose the business of course, so the early scientific results were positive (regarding light and reversible side effects).
Anyway, to make the long story short: avoid at all cost both SR and Finasteride/Dutasteride if you want to preserve your sexual health, unless you've serious prostate problems. If you also suffer from ED/PIED, SR/Finasteride could make the recovery even harder (you won't even understand if ED depends on porn or your treatment), so there's no sense at all in using them.