"We do not support Linux but we have received reports from other users who have successfully used our Thunderbolt 3 devices on an Intel NUC running Linux. If it doesn’t work, I suggest to first install Windows in order to update the BIOS and the Thunderbolt firmware (NVM) of your Intel NUC. Once that is done, you can go back to Linux and try it again. If you find that hot plug doesn’t work as expected, I suggest to connect and turn on the device prior to booting into Linux.
If that still doesn’t work, update the kernel to the latest version and also check your BIOS settings. Try setting the Thunderbolt security level to legacy and disable Thunderbolt Boot support. See if that makes any difference."
Sigh. A little too much outlay for me to only find out it doesn’t work.
As a last effort, I guess I can ask Adnacom if they’ve seen/used this config (NUC + Linux + Thunderbolt PCIe expansion box) working out in the wild.