I'm pretty sure I remember reading a line or two somewhere in a college history book about this historical figure.
The copy on the website says, "For 1,200 years her existence has been denied. She is the legend that will not die--the woman who disguised herself as a man and sat for two years on the papal throne."
Now, there's an intriguing female character to play. Of course, someone would have to either build a sim around it.. or I'd have to find one where it existed. And a bit of research would be needed too.. on my reading list now.... (in my spare time)
More about the book, which is coming out as movie: here