Yes, seen lots of posts like that. It's important to make the distinction between the terms, to refute the idea that

trans women can lactate and therefore breastfeed

Just to clarify: being able to lactate is not the same as being able to breastfeed.

Lactate means to "secrete milk." Most women who've given birth naturally lactate within a few days, but for various reasons - such as latch problems, illness on her part or the baby's, painful or infected nipples, work schedules, other obligations - many find they cannot breastfeed. And some mothers don't wish to.

Some mothers find they can breastfeed, but are unable to make enough milk to be their infants' sole source of nutrition. A woman has to produce quite a lot of milk to nourish and sustain the life of a newborn until the child is old enough to start taking solid food.

Moreover, breastfeeding a newborn begins before a mother starts lactating. It usually takes several days (3-5 days) after giving birth for a new mother's "milk to come in." Prior to that, a new mother's breasts will secrete colostrum, a non-milk substance that's rich in antibodies. The purpose of colostrum is provide immune benefits to a newborn; it's a way a mother transfers the acquired immunity to pathogens that she has developed over her lifetime directly to her baby.

Many male humans secrete a milky-looking substance from their nipples when they develop certain diseases like pituitary cancer and hypogonadism that results in low testosterone. This is called galactorrhea. These men are often said to "lactate" and the discharge is often referred to as "milk." However, chemically, this milky-looking discharge isn't the same as a mother's breastmilk, nor does it necessarily even come close (these secretions are rarely sent to labs for analysis, so exactly what's coming out of these men's nipples isn't entirely clear).

Even if a man with galactorrhea did produce milk or something like milk, there's no way the secretions from his nipples could immunize or keep a baby alive. Coz there's no reason on earth why males with galactorrhea would be secreting antibodies meant/suited for newborn babies from their nipples, and the milky-looking secretions that come out of their nipples tend to be in small quantity. Whereas new mothers produce a fair bit of colostrum - and huge quantities of milk.

A week-old baby will be consuming 16 to 22 oz of milk per day, approximately 473 to 650 mL. Babies between 1 and 6 months will consume 19-30 ounces per day, or 570-900 mL, for an average of 25 oz or 750 mL a day. However, some exclusively breastfed babies will consume as much as 1,350 mL per day, more than 45 ounces.

Another feature of breastfeeding that sets it apart from lactating as well as having galactorrhea is that the makeup of a mother's breastmilk changes over the course of her child's life to give the child exactly the nutrients the child needs in exactly the right amount. How, exactly, this occurs isn't clear, but the relationship between mother and a breastfeeding baby is complex.

There have been a couple of anecdotal reports published in the sensational Western press over time of male "explorers" to "exotic" lands who've claimed they saw a case here and there of a man from a "primitive" tribe breastfeeding his child. I know the esteemed novelist Louise Erdrich says this is a tradition amongst some of the Native American peoples she has written about (she's a member of the Ojibwa, but has written about other tribes too). And of course, a few TIMs have claimed they've breastfed their children.

But AFAIK, there's never been a proven case of a male who was able to produce actual breastmilk similar to a woman's, nor to produce nipple discharge in anywhere near the amount of breastmilk a baby would need to stay alive and to grow properly.

However, if men could breastfeed, and the breastmilk were shown to be as as good for babies as mother's milk, then a lot of women and men would be all for it. For example, the man I had children with would have loved to have been able to breastfeed (out of paternal love, not coz of fetishism or for "validation"), and I would've been more than happy to share the job with him - or let him take it over completely.

Given how envious men are of women's reproductive and breastfeeding abilities, and how clever men are in areas such as science and technology, if men really did have the potential to breastfeed children, I'd think they would have figured out how to do so by now. STEM fields are full of AGP TIMs, many of them with pregnancy and breastfeeding fetishes. So how come none of 'em have solved the male and/or TW "breastfeeding problem"?

Of course, fathers can and often do provide babies with connection and comfort by holding them against their naked chests. Babies will benefit from the warmth, the skin-to-skin contact, the smell and the sound of their dads' breathing and heartbeat. Sometimes babies will try to suckle their dads' nipples in these situations. That's fine and can be helpful to a child, just as sucking on a pacifier can soothe a baby, especially in the intense oral stages of development. But it's not the same as breastfeeding.

I was under the impression there are many medications you shouldn't take while breastfeeding. I'm very certain artificial hormones should fall under that category

You are correct. Women are usually instructed to avoid pretty much every medication while breastfeeding, and some kinds of food and drink (alcohol, coffee, soda) as well. Artificial hormones that are known to carry risks to the health of adults could cause all sorts of harm to vulnerable infants. Only someone supremely selfish and/or very sick in the head would consider doing this to a baby.