There was a report on this on the BBC London news just now. A young female design student has produced a kit to enable men to breastfeed. She did finally mention near the end of the segment that not a single man has yet tested it. She wants to issue men with some sort of pump thing and domperidone, the drug which is banned in the US but which the US transwoman who 'breastfed' a baby last year bought in Canada. (To be fair, I think I read that domperidone is used here to help women with breastfeeding issues, but not men.)
Her rationale is that men often suffer from depression after a baby is born because they feel excluded and one of the things they struggle with is that the mother is feeding the baby and they can't.
My answer to that is Get over it! This is how it is. If the mother wants to breastfeed, your role as her partner and your baby's father is to support the mother. If she doesn't want to breastfeed, then you can get stuck in with bottle feeding. Either way, you can change nappies, bath and dress the baby, take the baby out for a walk, give your partner a chance to sleep, make your partner a cup of tea and a sandwich, do your share of the tidying, cleaning, cooking, shopping, washing up, laundry etc etc etc.
What you don't need to do is take hormones which would be passed on to the baby through this 'milk'. FFS.