The latest beta firmware has APIs available for low latency audio and video. These are the same APIs used for streaming, and are available for your Steam Link media applications.

Audio:
https://github.com/ValveSoftware/steamlink-sdk/blob/master/rootfs/usr/include/SLAudio.h
Link with -lSLAudio

Video:
https://github.com/ValveSoftware/steamlink-sdk/blob/master/rootfs/usr/include/SLVideo.h
Link with -lSLVideo