Literata Book
My preferred e-reader font is Literata Book.
For the past two years I’ve used a Kobo Libra 2. Installing fonts onto the Kobo is a simple matter of copying the files to the fonts
directory, though it is picky about the filenames. I install the bold, bold italic, italic, and regular variants.
Other fonts I have installed are: the standard Literata, Atkinson Hyperlegible, and Bitter Pro. But I use Literata Book most often.
$ ls -1 /media/KOBOeReader/fonts
AtkinsonHyperlegible-BoldItalic.otf
AtkinsonHyperlegible-Bold.otf
AtkinsonHyperlegible-Italic.otf
AtkinsonHyperlegible-Regular.otf
BitterPro-BoldItalic.ttf
BitterPro-Bold.ttf
BitterPro-Italic.ttf
BitterPro-Regular.ttf
Literata-BoldItalic.ttf
Literata-Bold.ttf
LiterataBook-BoldItalic.otf
LiterataBook-Bold.otf
LiterataBook-Italic.otf
LiterataBook-Regular.otf
Literata-Italic.ttf
Literata-Regular.ttf
I uploaded an archive of the fonts.