How about first collecting ideas on things which would actually help people (in addition to teaching)? I think Greece is a pretty high-tech society but maybe there is substantial "brain-drain" - still, I'd wager that it's mostly the economy which is broken.
I don't know if it's viable but something like a node based twitter bot that picks up on calls for help on greek facebook pages (e.g. "doctor needed!") and other twitter accounts which then gets aggregated on a website? It might be a very naive idea but I've got the feeling that setups like hackathons (where all kinds of interested people can participate, people people, idea people, technically inclined people, etc) can be more beneficial to learning than a traditional "school" like environment but maybe that's just me (and my inherent learning style).
I know of some fellow Austrians who might be interested in helping out as well, please reach out if you could need further help.
I salute you for your actions - I feel like it's all about love and solidarity in order to overcome our global problems <3