Can't guarantee my links below, some links may not still be available.

Don't take all of these each day, just find ones you like, I did rotations but these were the ones I would say I like:
Boron
Lycopene/Tomato
Neem and Ginger
Crinum Latifolium
CLA and Modified citrus pectin
Iodine
Boswellia
Also take some NAC for your liver

Boron - 6 mg, liquid
Boron Reduces Prostate Cancer Risk
Nothing Boring About Boron
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4712861/
"has demonstrated preventive and therapeutic effects in a number of cancers, such as prostate, cervical, and lung cancers, and multiple and non-Hodgkin’s lymphoma"
Dietary boron intake and prostate cancer risk
https://pubmed.ncbi.nlm.nih.gov/15010890/
Lycopene, 20 mg
The Potential Role of Lycopene for the Prevention and Therapy of Prostate Cancer: From Molecular Mechanisms to Clinical Evidence
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3742263/
Lycopene effects contributing to prostate health
https://pubmed.ncbi.nlm.nih.gov/20155615/
Is there a benefit from lycopene supplementation in men with prostate cancer? A systematic review
https://www.nature.com/articles/pcan200938
Neem, Ginger
Ginger
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3426621/
https://onlinelibrary.wiley.com/doi/abs/10.1002/jbt.22611
Neem
Neem components as potential agents for cancer prevention and treatment
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4734358/
Consumption of a bioactive compound from Neem plant could significantly suppress development of prostate cancer

Crinum Latifolium
Crinum Latifolium Leave Extracts Suppress Immune Activation Cascades in Peripheral Blood Mononuclear Cells and Proliferation of Prostate Tumor Cells:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3134856/
CLA and modified citrus pectin
https://pubmed.ncbi.nlm.nih.gov/14976130/
Both discussed:
https://www.lifeextension.com/magazine/1999/10/report4
Boswellia Serrata / Frankincense
https://aacrjournals.org/cancerres/article/68/4/1180/542608/Acetyl-Keto-Boswellic-Acid-Induces-Apoptosis
https://www.sciencedirect.com/science/article/abs/pii/S000629520800172X
Iodine (more advanced should use, not for everyone)
I don't have a thyroid (cancer) so I can take a fair amount or a lot, but don't do that if you have a thyroid, just a slight amount over RDA.
The Link Between Prostate Cancer and Iodine
https://www.biowarriornutrition.com/blogs/blog-page/the-link-between-prostate-cancer-and-iodine
A prospective study of iodine status, thyroid function, and prostate cancer risk: follow-up of the First National Health and Nutrition Examination Survey
https://pubmed.ncbi.nlm.nih.gov/17571964/
Iodine Uptake and Prostate Cancer in the TRAMP Mouse Model
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3883964/
Just be aware the taking of iodine and not having good or adequate selenium levels is a known trigger to cause Hashimoto's disease. So that means if you choose to take iodine or more than RDA, have your primary care run a selenium lab first because if it is deficient that can cause a bad outcome.

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See also this guy who uses completely differing supplements and has some success, my supplements didn't ever lower PSA, I find ones that reduce PSA not great as they are often just like taking finasteride. Anyway, this person uses other supplements than I mentions above:
https://iloweredmypsa.com/