Valve has released a software development kit to allow native application development for the Steam Link, Valve's hardware that allows you to stream from your PC to your TV.
Everything you need is available on this GitHub link.
The Steam Link hardware is a single core ARMv7 processor using the hard-float ABI, running at 1GHz, with neon instruction support. It has around 256MB of available RAM and 500MB of usable flash storage.
As for the software, it's custom Linux firmware based on kernel 3.8 and glibc 2.19. The Steam Link SDK has support for OpenGL ES 2.0, Qt 5.4, and SDL 2.0.Valve points out that the SDL game controller API is recommended for Steam Controller support on the Steam Link.
The SDK contains examples of applications, source code to 3rd party components of the Steam Link, Linux kernel source code, the Steam Link root filesystem, GCC toolchain, and a script to configure the build environment.
In our testing of the Steam Link, we found it a capable piece of hardware and great for its price, unfortunately let down by frequent issues with Steam In-Home Streaming.
In other news, last week Valve also added quadraphonic and 5.1 surround audio support to the latest Steam Beta Client for in-home streaming. Your Windows host doesn't need to support 5.1 audio to use this feature. Support is already included in the latest version of the Link firmware. Valve is currently "investigating adding 7.1 audio support to both the Steam Client and Steam Link."