Hi -
I've been running High Sierra since shortly after it was released on my Skull Canyon NUC pretty successfully. Audio worked great (and had full sound - bass came through strong). I use wired ethernet and a Bluetooth dongle. I use the HDMI and mini-DP ports for displays, the former to a 4k TV, the latter to a 1080p display via a mini-DP to HDMI adapter. The only hiccup is that if I booted with the mini-DP display attached, it wouldn't work properly. Not a big deal. I don't reboot that often, so I just needed to remember to unplug it before rebooting and plug it back in when the system was up. It lit right up.
I updated to Mojave this afternoon. I've been using RehabMan's nuc.git for a while, so I pulled updates, downloaded the tools, installed them, did the make clean, make install_nuc6sc. I updated the config.plist to match config_nuc6_sc.plist, with the exceptions being the serial numbers and my default volume.
The primary display works at 4k (but seems a little sluggish -- e.g. launchpad takes a few seconds to fully render, but Chrome scrolling is fine). I *think* prior to updating it reported as "Intel Iris Pro Graphics 530 1536 MB" but now it reports as "Intel Iris Pro Graphics 580 31 MB." I could be wrong about the 530 vs 580 but can't easily go back to confirm it. Audio "works" in that I hear sound coming from the speakers attached to line out but (as I've seen others report) there's a noticeable lack of bass where the bass was fine prior to updating. Using the headphone jack improves the bass situation, so there's at least a workaround.
So, it's mostly there.
The big issue I'm facing is that the mini-DP -attached display isn't recognized at all, whether I boot with it plugged in or not. Strangely, the display icon in the menu bar reports a projector is attached. It's enabled as a separate display but the cursor doesn't leave the primary display and the options to position a secondary display aren't presented in system preferences.
I tried booting with my old clover config.plist (and manually re-enabling the ig-platform-id to what it was prior to updating) but nothing has had any effect.
I've attached the output of black.dragon74's script. Hopefully there's something in there that can provide a hint as to why the second display isn't working anymore.
Thanks for any help,
-Jeff