Strictly speaking, you can connect the STM32 directly to an Android in a similar fashion to how the IOIO does it, without needing a IOIO in between.
However, it is a lot of software work. You may be lucky in finding that someone already did this as an open-source project, or otherwise you're probably looking into weeks of development, depending on which kind of communication you actually want.
Personally, I'm not looking for a freelance project, but perhaps someone else on this forum does. I'll be happy to answer specific questions asked here, free of charge :)