Im not familiar with the technical intricacies of smartphones, but Id assume another issue is that hardware components may vary, even within what is sold as the same model, eg accelerometers sourced from whoever is cheapest and can deliver. These hardware differences may affect software, and if a team of cabable programmers wanted to launch a commercially feasible product for semi-professional use, they would probably need assurances that all critical hardware components won't be changed for a few years. The way consumer product supply chains work, that seems unlikely.