How to read a book aloud?
Go to this link
Read aloud and add your book there. Then you can open and read aloud a book. (You need double click some text.)
Can I read a PDF book aloud?
Yes, if PDF contains some text.
Can I read aloud other file then PDF?
Yes.
Read aloud can open and read aloud many file formats.
I cannot choose a different voise?
It depends on your system and browser. Desctop Edge browser has many natural voices.