For me, running it on my home server so it can save my progress would be good.
pandoc -f epub file.epub -t plainit saves the state of having the narration on or off, so if you ever open the book again you don't hear any voice. also the reading progress and state is automatically saved to your system log files. I'm pretty sure with a few settings in the config.py file you could direct them to your server.
about the monospace fonts. yes, they're not the prettiest but they're very easy to read! easier than many much more beautiful fonts. and if you're tired of reading, just switch on the tts. ;)
me, mainly i just look for the most beautiful monospace font i can find that has a nostalgic feel. recently my favourite has been "modeseven" (https://online-fonts.com/fonts/modeseven), which is also featured in the screenshot on the github page.
+ from rich import box
...
book_panel = Panel(
book_content,
+ box=box.SIMPLE_HEAD,
title=f"[{COLORS.PANEL_TITLE}]{progress_text}[/{COLORS.PANEL_TITLE}]",
...