Are there female soldiers within the ranks of the lunar military? Yes, the Lunar army has female soldiers and leaders.
Going back to my post yesterday about the main cults in the Heartlands, about a quarter of the population belong to the Seven Mothers. About 14% belong to Lodril, and about 10% belong to various celestial cults (Yelm, Polaris, Shargash, etc.). So that gets you about a third of the population that are potentially decent recruits as soldiers. Of that, probably around one in eight are women.
Some regiments might have more or fewer women, but women soldiers are common enough that I doubt many Lunars think twice about it.