So my PC is now in the bedroom where I'm running it headless - or at least trying to. It's been an interesting experiment into the viability of exclusively using it as a game server to say the least...
First of all, it refused to work with VNC without a monitor being plugged in. I kind of expected that because the graphics card can't see an output so why would it work? I was surprised there wasn't a virtual display driver installed along with TightVNC or Splashtop, though.
Steam streaming did work, though, so I thought OK, I'll use that and set up OpenSSH for admin access (like for cleanly exiting games if the stream dropped and for shutting down/rebooting), but my OS is flat out refusing to let me set up the SSH server which sucks.
So the next step was to get an EDID spoofer so the graphics card would "detect" a "display", so I ordered a Fit Headless GS from Amazon US about a week ago, it arrived today and it has fixed the VNC problem perfectly; I can tell my PC I've got anything up to a 4K 60Hz screen connected and Splashtop works without issue now.
So, back to Steam streaming... My MacBook Air performs perfectly well, barring the occasional network hiccup (it's on 802.11ac, PC is wired through 100Mb ethernet), but it's the ancillary stuff that ruins it. I tried Hitman, but the stream crashes when it transitions from the launcher to the game. I can fix it with Splashtop but shouldn't have to, right? My Xbox One Elite controller doesn't work with my Mac so I have to use a DualShock 4, I don't really like it but I guess it'll do. I can't get Forza Horizon 3 or Motorsport 7 to stream at all, it launches but then cuts the stream AND blocks Splashtop, so I have to use VNC to get in and close them. Wreckfest doesn't see the controller, either, and that's probably the game I want to play the most.
Then I remembered Moonlight, the open-source Shield streamer, is a thing. That in turn reminded me that I bought an Ouya almost specifically to get an Android device with HDMI and an Ethernet port... But I couldn't find the power supply, so I downloaded the app on my phone instead and was really impressed by how smooth it was considering that it can't do the Steam Link app - its an Xperia Z5 Compact. I still couldn't use my Elite controller with an OTG cable but could connect the DS4 via Bluetooth and I was able to play Forza Horizon 3 without issue as that uses GeForce Experience instead.
I have a Steam Link on order but I don't expect it'll arrive soon as I haven't even had a dispatch note yet, I expect - if it works - I'll end up switching between it and Moonlight running on the Ouya depending on what I want to play or which controller I want to play them with... I don't know if the Ouya will work with a DS4, after all.