It's hard finding any info about this, so I wanted to share here what I've found.
According to 01.org(Intels OSS stuff):
Networking over Thunderbolt cable was introduced in v4.15 kernel
This is a very new kernel (i.e. at 10April 2018 CoreOS only offers it on their Alpha-channel).
It does sound like it's perfectly possible if I must believe Phoronix with this new Linux-version:
The patch offers a new THUNDERBOLT_NET option to support creating a network between multiple computers using a Thunderbolt cable. This Linux driver supports the Apple ThunderboltIP protocol and supports any host using this protocol, including Windows and macOS.
lwn:
Thunderbolt Networking for Linux is compatible with Thunderbolt
Networking on systems running macOS or Windows and also supports
Thunderbolt generation 2 and 3 controllers.
1- https://01.org/thunderbolt-sw/overview
2- https://www.phoronix.com/scan.php?page=news_item&px=Thunderbolt-Network-Linux
3- https://lwn.net/Articles/705998/