Elmren Voice is a Mac app for family read-along and for turning EPUB, PDF or DOCX files you have rights to into chaptered M4B audiobooks. The read-along can use a built-in voice or a voice recorded with permission, and it is saved as one HTML file that opens in a browser on a phone, tablet or computer.
It is free to try with 120 synthesis minutes within 7 days of first run. After that it is $39.99 once, for one Mac. It requires Apple silicon (M1 or later) and macOS 13 or later.

I wanted family read-aloud nights, and a separate way to turn my own manuscripts into audiobooks on a Mac. So I built Elmren Voice to do both.