I've been searching for something like this for a while and have not found anything suitable. Honest question: do you have pointers for any of the other devices you mention?
also gp2x https://en.wikipedia.org/wiki/GP2X (discontinued but you can find them on ebay). Comes in 3 models, GP2x, GP2X Caanoo, and GP2X Wiz.
I had one as a kid and loved it. Got into Linux and programming because of it.
Or a rooted old android phone is pretty similar, more functional than the WiPhone, and probably cheaper as well.