It seems like you have a pretty good idea of what you want to do. That said, assumption number 3 is not entirely true. Pocket (which is already widely used) has

It seems like you have a pretty good idea of what you want to do. That said, assumption number 3 is not entirely true. Pocket (which is already widely used) has TTS tech integrated and it's really easy to use. I could see the value so long as the articles are narrated by a human. A condition that, like you said, seems to have a lot of strings attached to it.