Have you milk a cow before? No ! You don't need to anyway, here's a idea so here me out , are you ready ? Make mini game were you need to pleasure the ,,cow" in order for her to reales milk.
That an idea lol ;)
Did you plan to release the game un the future for android ?
Just in case anyone wanted to play the game but can't do it on PC cuz they have to share the pc with someone is ok , for now you can try Joiplay.(not add or promovation is just what I use to emulate games in Ren py/ Rpgmaker)