>>wicket+(OP)
Apologies if the idea is absurd, but wouldn't a Linux handheld without a cell modem be easier to build and distribute? Think something of an analogue to iPod Touches, which were iPhones sans the the phone part.
This would skip a lot of the regulatory red tape, bring down costs, and make the devices more accessible so they’re in more developers’ hands. They’d have to tether from your primary phone which isn’t ideal, but workable.