Answered my own question:
If you already have a favourite online retailer, you can install Kindle, Kobo, Nook, Scribe, Libby, Tolino, or third party apps such as Koreader or Moon+ Reader.
https://goodereader.com/blog/reviews/meebook-m7-e-reader-review-a-great-all-rounder
The follow up is how does using these compare to a kindle?
A case swap without any loss of functionality is pretty substantial. Sure its lots of work to get right back where you started (a working device), but that doesn't mean they did nothing.
The effort to do it so seamlessly is pretty incredible, in my opinion.