I have a friend currently gender transitioning and he is struggling with having too high of a voice. He'd like to make YouTube videos and podcasts, but the voice pitch is a serious problem for him. He's tried some various out of the box apps that do voice pitch changes and they really seem to work well for male to female, but all of them fail miserably going from female to male.
In 100% of all tests the pitch shift has been detectable and he's already gotten some challenging feedback that clearly demonstrate that he's not going be able to push through this without some help.
What options exist for properly pitch shifting a female to male voice without evident artifacts from such a software pitch transition?