FBReader might be an option. You can upload books using the FBReader Book Network, which uses your Google Drive as storage, and then use it to access your books and synchronize your progress across a variety of platforms.
I wanted to install it on my Pinebook Pro (AARCH64, with Tow-Boot installed to SPI) but I haven’t gotten it working.
I was using Firefox back when it was cool. And now it’ll be cool again.