> I would love the option to switch to a more natural voice for more literary text (or even a fan fic) so I'll definitely be checking this out
I'm curious if it would be possible to do some kind of analysis to determine the number of individual characters in the text who are speaking, and then assign an appropriate voice to each of the characters. So if you had something like descriptive language interspersed with a conversation between two characters, that you'd have three voices (a narrator, Character A, and Character B) that are consistent across the text.
For more complex writing with many characters, you'd probably need a wide library of possible voices, and the analysis piece would need to spot-on, since it would be very confusing to have one characters' lines spoken by the wrong voice.
Regarding fanfics, many authors give (or withhold) permissions around creating derivative versions of their work via avenues like ficbinding. Before using a tool like this to create an audio version of their writing, I'd suggest reaching out to a fic's author to see if they'd be okay with that. For personal-only use, though, and especially if it's in context of accessibility for visually-impaired folks, I imagine that many of them would probably be okay with it.