I think you have hit the nail on the head with this one. There isn't an environmental problem (that I know of) with ceramic cups, we just need to work out a way to get people using them instead of the disposable ones. There's a juice bar next door to where I work that does exactly what you describe (they sell salads in mason jars, for which you pay a deposit. So there's definitely a precedent for this sort of thing.
I wonder if manufacturing could be brought "in-house" (for instance - not wishing to jump to solutions, but just to illustrate the point - by providing communities with a 3D printer or similar). A solution that puts manufacturing in the hands of the community might avoid some of the economic issues you mention. I realise that this still leaves the problem of the sustainability of the raw material. However, shifting manufacturing closer to the consumer (and making it easy) may be an avenue worth further thought?
I like that this idea is potentially scalable, i.e. once you finalise exactly what the hardware and software looks like, you could potentially prototype pretty quickly. One thing that I haven't seen really addressed in any of the ideas I've read though, is what kind of knowledge / education we should be providing to refugees? I agree that there may be local info / news that they need, but beyond that, I wonder if traditional education topics (maths, chemistry, etc.) are the most relevant to their situation - perhaps, for instance, a course in Design Thinking might help them to develop solutions to their own current problems; or, maybe something directly practical, like carpentry. I'm not arguing that refugees don't deserve access to all kinds of learning (they do), just making the point that if only one or two educational resources "make it" to the learner, you want to be sure that its the most useful info they could have.