I am not against pragmatic herbal remedies when they actually work (in fact, I vastly prefer them). I grow and harvest my own passionflower, for example, as a sleep aid. Drugs are drugs, they work regardless of whether you make them in a lab or grow them in a plant. Opiates work just as well from poppy seeds as they do from a pill, for example.

As I mentioned earlier, I also turned to herbal remedies for anti-androgen effects, though I actually used herbs that were shown in (admittedly, limited) scientific studies to lower testosterone, like licorice root, flax seed, and spearmint. I did not find this anywhere close to a suitable substitute for HRT, nor was it particularly effective at blocking testosterone. I continued to have male levels of testosterone in my blood when tested, and I continued to have physiological signs of that testosterone (body odor, involuntary erections at night, ample semen production, etc.).

However, gemmotherapy is categorically not an effective method, it is a kind of homeopathy that makes false claims about the special healing or medical properties of plant embryonic tissue extracted during germination - this is not based in the actual chemical or medical sciences that examine the effects of phytochemicals. That's what makes it pseudoscience.

Of course it is possible still that the hops plant contains chemicals that have anti-androgen effects, but I go back to my original question: how does it work? I want to know what dose and preparation is actually effective, and why. What are the risks and side effects? This is no different than taking other drugs, because it comes from a plant doesn't make it inherently safe.

Homeopathy dilutes chemicals to the point that they have no medical significance, purported benefits are thus placebo. It's not clear to me whether gemmotherapy is likewise diluted or if you are actually consuming an extract with pharmacologically-relevant doses of the drugs. Your own experiences with blood testosterone levels dropping could be explained by the estrogen patches you were taking, if they got your blood estrogen levels consistently up to 200 pg/mL or higher, as that would be sufficient to block testosterone production.

If you are relying on the phytoestrogens of the hop plant as an anti-androgen, it's not clear to me the risks of using phytoestrogens is worth the anti-androgen effects of that lesser form of estrogen, considering you already have access to bioidentical estrogen which is known to be much safer and directly estrogenizing than taking phytoestrogens. Monotherapy (where you take a large enough dose of estradiol to block testosterone production) would make more sense to suppress testosterone in that case than taking a hop extract in addition to estrogen patches (in terms of money, safety, and efficacy).

Maybe there are other anti-androgen chemicals in hops, but again I just want to know what those are, how they work, etc. - just like I would want to know about any other anti-androgen drug I would consider taking.

And of course, if HRT is taken away from you and you have no patches and nothing but phytoestrogens, it's probably better than nothing (maybe - perhaps especially for pre-op and non-op women). I've looked into growing wild yams to extract phytoestrogens from, for example - but they rarely work the same or as effectively or safely as bioidentical estradiol, and usually you need a lab to meaningfully extract and convert those phytoestrogens into a useful estradiol.

In a context where estradiol is not available, the best source of it would actually be urine from cis women, since they excrete hormones directly in their urine (and probably from pregnant women since their hormone levels are typically much higher). Extracting the hormone from the urine and controlling the dose however would be difficult and require industrial inputs, e.g. methanol and silica gel. But in a worst case scenario you might get enough estrogen from a pregnant woman's urine to help, though if we're not extracting and injecting the estradiol and just drinking the urine, the liver will absorb ~80% of that estrogen and your blood levels will spike and elimination half-life is a few hours. So you will end up needing to drink urine a few times a day, and pray that there's enough estrogen in that urine to be enough.

This random website I found claims peak estradiol levels in urine just before ovulation are around 14 mcg / mL, so drinking 500 mL of urine might give you at most 7 mg of estradiol, which seems decent for an oral route of administration, you might even drink half of it in the morning and the second half in the afternoon to help try to maintain more normal blood estrogen levels throughout the day.

So I think this is the most plausible way to get estrogen in a context where HRT is not available, but it sucks for a lot of obvious reasons. This is truly under apocalyptic conditions, though - ideally you would just find a grey or black market to buy the drugs through, because most likely there is someone around still manufacturing estradiol since even cis women need and thus society in general is invested in its production.