Not sure if this would qualify for mvp or if this model would even work at all, but I'll put it out there anyway.

GidiBooks is an ebook marketplace. Basically, people just buy and sell PDF ebooks. No registration required to buy. The pdf files can be transfered across your devices for offline reading as you would with a regular PDF file.

Perks associated with registered accounts include saving download links of previous purchases and access to 'GidiBooks Funds' which is basically a topup functionality. Merchants take 90%.

Functionality feedbacks or ideas if you have the time. Thank you.

Also, you could try out the service with this short story I wrote for this purpose. A Little Too Late. It's free.