The Raspberry Pi 5 now works as a smaller, faster kind of Steam Link
The Steam Link was a little box ahead of its time. It streamed games from a PC to a TV, ran 1,500 0f them natively, offered a strange (if somewhat lovable) little controller, and essentially required a great network, Ethernet cables, and a good deal of fiddling.
Valve quietly discontinued the Steam Link gear in November 2018, but it didn't give up. These days, a Steam Link app can be found on most platforms, and Valve's sustained effort to move Linux-based (i.e., non-Windows-controlled) gaming forward has paid real dividends. If you still want a dedicated device to stream Steam games, however? A Raspberry Pi 5 (with some help from Valve) can be a Substitute Steam Link.
As detailed in the Raspberry Pi blog, there were previously means of getting Steam Link working on Raspberry Pi devices, but the platform's move away from proprietary Broadcom libraries—and from X to Wayland display systems—required "a different approach." Sam Lantinga from Valve worked with the Raspberry Pi team on optimizing for the Raspberry Pi 5 hardware. As of Steam Link 1.3.13 for the little board, Raspberry Pi 5 units could support up to 1080p at 144 frames per second (FPS) on the H.264 protocol and 4k at 60 FPS or 1080p at 240 FPS, presuming your primary gaming computer and network can support that.