Note that you can do point-to-point network links directly with thunderbolt (and usb4).

https://support.apple.com/guide/mac-help/ip-thunderbolt-conn... etc

Yes! However, I got around 15 Gbps with a Thunderbolt-only setup (TB3/TB4) = only 75% of the Ethernet setup.

You'd also mostly be limited to short cables (1-2m) and a ring topology.