As mentioned, a mere Solu app will not suffice. It's not just the limitations on AppStore/Play etc, we do actually go down into the kernel level to make this whole model work.
Technically we could provide a complete OS that you could install to replace, for instance, OS X, but then we would need to be very conscious about the many different hardwares we would have to support and, also, this would cut out most of the people out there who would never even think of installing a new OS on their machines. There is a strong psychological link between the hardware and OS.
Solu is a great piece of hardware that you can connect to many kinds of displays out there. You get a guaranteed good experience. You can use it on the go as a mobile device. It's beautiful and made in Finland, and actually pretty inexpensive for what you are getting. I think it's a pretty good offer :-)