The QNAP 10 Gbit/s Thunderbolt Ethernet adapter seems to work. Model: QNA-UC10G1T.
The controller is not enabled and authorized by default.
The only thing I added is a new Init/Shutdown Script (System/Advanced Settings).
Type: Command
Command: /bin/echo 1 > /sys/bus/thunderbolt/devices/1-2/authorized; sleep 20; /bin/echo 1 > /sys/bus/pci/rescan
When: Post Init
Timeout: 120
The interface will then be available in the system/network section.