Valve has overnight launched Steam Link Anywhere, an update to their Steam Link service that allows people to stream their Steam games to other devices, so that it can now be used across the internet, and not just on a local network.
As per the announcement, Steam Link Anywhere now will let you stream your games from 'any computer running Steam, as long as your computer has good upload speed and your Steam Link device has a good network connection.' There doesn't appear to be specifics on what consitutes a 'good network connection' at this point however.
The company also announced that it was releasing new Networking APIs to all Steam partners, that lets developers take advantage of Steam's networking backbone that powered CS:GO and DOTA2's multiplayer experiences for their own games.
Valve has contintued to evolve the Steam Link app after retiring the hardware version a few months back.