Ok here's what I've found out since your reply.

1. I've confirmed that the USB C ports on the LG monitor don't work.
2. I don't have any other Thunderbolt devices, but I have a USB C hub which has Gigabit Ethernet, HDMI, VGA, SD card, and several USB ports. The Ethernet, HDMI (and I assume VGA) all work fine so I assume that this means the Thunderbolt is passing more than just DisplayPort.
3. However, despite #2, USB or SD Card does not work. I think for some reason you need to supply a USB connection to the Titan Ridge. I know there's a USB 2.0 header connection on the circuit board, and there's a cable in the box, but obviously there's no way to connect that to the Mac. I would maybe need to get a USB header to USB A cable and pass it through to one of the ports on the back of the Mac. If anyone knows if this works let me know!
4. If I get USB working, then maybe the USB functions of the LG monitor will work (ie Webcam, Speakers, Mic, USB ports, maybe even brightness control).
5. Despite the USB C hub working, the Thunderbolt section of System Information shows as 'No Device Connected'. This could be because it's not a Thunderbolt device though, because the hub DOES show up in the USB section.
6. It's possible to hot plug the monitor, so no need to shutdown first. The only caveat is you need to power cycle the monitor for it to be recognized. So I guess technically it's the Thunderbolt device that can't be hot plugged, if this makes sense?
7. Maybe most importantly: When I boot up with a device connected to each Thunderbolt port (in my case the 5K monitor and the USB C hub), the Mac doesn't boot! If I connect the USB C hub AFTER booting then it doesn't show up. The only way I can get the USB C hub to work (as described in #2) is to not have the 5K monitor attached. I'm curious if the 5K monitor is just using up all of the bandwidth.