Amsterdam UMC finally agrees that adding progesterone to feminizing hormone therapy may be a good idea (on a trial basis): www.news-medical.net/news/20250905/Adding-progesterone-to-gender-affirming-hormone-therapy-improves-breast-growth-for-transgender-people.aspx
Adding progesterone to gender-affirming hormone therapy improves breast growth for transgender people

The addition of the hormone progesterone to gender-affirming hormone therapy leads to increased breast growth for transgender people following feminising hormone therapy.

News-Medical
i am pretty sure trans people have known that progesterone can be helpful, since before we were born. but at least the Dutch trans healthcare situation got slightly less bad, i think!