Remote PC viewing
Would it be possible to make the Pi a VNC viewer? The use case for this could be for presentations or demos where a PC desktop is required, a PC can have the VNC server broadcasting a (view only) stream of its desktop. The Pi can then view this stream?
There's a couple ways you could accomplish this without VNC through software or hardware.
As we have recently discovered, you could use the "HDMI extender" recommended by Yodeck's video wall documentation (Lenkeng LKV373A) for this. Connect the PC's video output to an HDMI splitter, the HDMI splitter to both the user's display and the HDMI extender, and connect the extender to your network with an ethernet cable. It will grab a multicast IP address. In Yodeck, you can then add a video stream media object, and point it to "udp://[multicast IP]". Then you'll have a live display of that PC's screen at all times from any Yodeck display, with about a one-second latency. This is definitely not the cheapest or easiest way to do it, but it will require zero intervention from your users and no software to be running on the client machine.
Alternatively, any software that can broadcast the user's screen to the local network over multicast should also work! Apparently, VLC and OBS can both do this.
I am also looking into how to make this happen, but for a completely different purpose. Our company is wanting to have a window that tracks our warehouse employees' order pulling progress rotating in the display for customers that come into the facility. If you can think of a good way to handle that, I'd love to hear how!