default or selected kernelversion does not have config value CONFIG_THUNDERBOLT_NET.
Result is shown for kernelversion 6.8.2

Networking over Thunderbolt cable

modulename: thunderbolt-net.ko

configname: CONFIG_THUNDERBOLT_NET

Linux Kernel Configuration
└─>Device Drivers
└─>Network device support
└─>Networking over Thunderbolt cable
In linux kernel since version 4.2 (release Date: 2015-08-30)  
Select this if you want to create network between two
computers over a Thunderbolt cable. The driver supports Apple
ThunderboltIP protocol and allows communication with any host
supporting the same protocol including Windows and macOS.

To compile this driver a module, choose M here. The module will be
called thunderbolt-net.

source code: