The Lynx browser runs on DOS:
https://archive.org/details/msdos_doslynx_browser
If I'm bored I'll test it in DOSbox (runs on everything, inc ARM phones: Symbian, iOS, Win CE, Android) or any x86 native DOS.
But I'm surprised I didn't find a Mobireader for DOS as the Palm OS one is Text based and the Symbian one is simple. Likely people used Win 3.0 on very basic hardware and an ereader on that.
A DOS one likely doesn't do images.