Valve have today announced a Beta version of the Steam Link app for the Raspberry Pi which could prove to be interesting.
Since Valve are seemingly discontinuing their own Steam Link device, along with creating the new Steam Link applications for mobile devices, one for the Raspberry Pi does make a lot of sense. I imagine quite a number of people already own the device, so being able to stream your favourite Steam games to it is probably quite appealing.
Specifically, the Pi 3 and 3 B+ are supported running Raspbian Stretch (A Debian-based Linux distribution). It can be installed directly from a Valve-provided .deb file and in the comments on the announcement Valve also linked to a Debian source package (after someone said about an arch PKGBUILD).
I imagine the Raspberry Pi folks are pretty happy to see Valve do this too.
See the full info here.