Fold, for sure. Actually pocketable, and secure once pocketed.

I have an e-ink tablet that runs Android. Copes with most apps and can deliver stuttery video.

E-Ink can’t be far off replacing glass screens (at least as an option) because the benefits for battery life are substantial. But I’d think it would replace them rather than be in addition to. A phone with screens on both sides would be so fragile.