…yes, at first I wasn’t that interested in the Orba, but the Artiphon Instrument made me reconsider as I’ve started messing around with that lately, and it’s a pretty good piece of design really. (You can tilt it on its strap for expression the same way melodic_malloc is thinking about with the Linnstrument.)
The Orba isn’t especially cheap though. But after you posted about it I looked on eBay again and impulsively purchased a faulty one for thirty quid . (“You can’t delete loops”. Dunno what that’s about. We’ll see.)
Using the accelerometer in an Android phone as a MIDI controller seems quite a well-trodden path. Eg