Societies, and even families, that seek to keep a target population oppressed will keep that target population illiterate. They must either be taught to read or be contacted person-to-person in some other way.

My contacts with literacy people in the US have taught me that, though battered women are not the only illiterates, they are the ones most likely to encounter resistence and violence from the authority figures in their lives when they begin to seek to learn how to read. The batterer views reading, rightly, as a threat to his or her control over the battered partner. Social oppression is a kind of institutionalized battering. A battering government would have at least as much vested interest in continued ignorance and debased self-concept of the population as a bullying partner would on the smaller scale.

I think your basic concept is sound, though: knowledge is power. You have to start with knowledge. The occasional outburst of blind rage is cathartic for victims, but not transforming the way knowledge and ideas can be. The abilities of the audience to access the knowledge must always be kept in mind.

Radio springs to mind. It's old-fashioned, but it's tried and true, and little radios are remarkably tough -- a lot tougher than the screens on lappies are, anyway. Something to consider for the airdrop option.

For secrecy, include earbuds.