You reinvented...the keytar.
I miss the Sidekick, myself. Was the perfect device for writing while standing. Physical keyboard and a big-ish screen, with the form of a modern smartphone.
The swivel design made finding a decent case tough though. And there were few apps.
I have a keyboard that I've attached a guitar strap to, in order to be able to type while standing, without a table to rest the keyboard on.