Tips for e-readers

I've read on both Kindle PaperWhites and a Kobo Libra H2O. They're both fine!

Fonts

How to add custom fonts to a Kobo e-reader + Bookerly link: Plug in your Kobo e-reader, create a folder called "fonts" in the main directory. Add the .tff files directly to that folder (no subfolders). They must be named in the pattern of FontName-Style, and for style Kobo seems to accept Bold, Italic, and BoldItalic. So for example:

fonts/ 
    Bookerly-Bold.ttf        
    Bookerly-BoldItalic.ttf  
    Bookerly-Italic.ttf      
    Bookerly-Regular.ttf
    LibreBaskerville-Bold.tff
    LibreBaskerville-BoldItalic.tff
    LibreBaskerville-Italic.tff
    LibreBaskerville-Regular.tff
    Spectral-Bold.ttf
    Spectral-BoldItalic.ttf
    Spectral-Italic.ttf
    Spectral-Regular.ttf

Some good fonts for e-reading

Managing e-books on a Linux desktop

I have used and like Calibre.

For improved reading/organization of certain file types on your Kobo device

I think koreader is a replacement for the default software on your e-reader?

There's also a Rust program for handling PDFs and other difficult filetypes: https://github.com/baskerville/plato

Kobo ebook store

How to add books to a Kobo e-reader