The Amazon Kindle has a browser through which you can access some sites that aren't too complex or cumbersome.
It can even access the Faithlife domain "biblia.com", log in with your Faithlife/Logos account and access the library and open the books to read in the Kindle browser.
However, when accessing the site via Kindle, there is no option to increase the font to make reading easier. Even so, it is still possible to read Logos books in the Kindle browser with a little effort and good eyesight. Test it out to see if you can use it and improve its usability.
My suggestion is for Faithlife to work with the team of developers to find a way to adapt the "biblia.com" or "app.logos.com" sites or, perhaps, even create a simpler specific site for this.
The site's features could be completely adapted just to provide basic reading functions. For example:
1) home page with larger icons to facilitate access and login;
2) library option to locate Logos books;
3) easy option to enlarge the letters of the books;
4) perhaps even a basic option to underline and mark books.
This way, with simple functions, we'll be able to read Logos/Verbum/E-book books in the Kindle's built-in browser. The advantage of this is that we can read on the e-ink screen which doesn't strain the eyes like LED displays etc.
Please study this possibility. It seems quite feasible since it is already possible to read the books on the "biblia.com" website, albeit precariously.
Vote for this idea here in Feedback (Faithlife).