Mazikeen has been on a very emotional journey throughout these four and a half seasons, and her most recent obstacle has been her feeling of inadequacy because she lacks a soul. She teams up with Michael to procure one, but neither one has explained how exactly that will go down. Both Lucifer and Amenadiel have said that it's never been done before, though the latter is more open to the possibility of Maze being the first demon to accomplish the impossible.
My big theory is that Maze already has a soul, but isn't able to tell. It's easy to see that she's unlike other demons, her time on Earth has changed her remarkably, even if the big plots of the season tend to regress her growth. I wouldn't be surprised in God reveals that Maze has gained a soul purely from her journey to loving others (Trixie and Linda, specifically) and wanting to make a life for herself.
I also hope that discovering her soul will help her find her way back into the arms of that hunky Ben Rivers (Chris McKenna).