is there a way to monitor when the tb connector is plugged in what the MB does
Look at Hammerspoon.
it might have a preconfiged spoon add on you are looking for. Or you can right one yourself in lua.
Something should appear in the log when a Thunderbolt device is connected. Check the log stream command. Learn about predicates for filtering the log messages.
You can turn on pci debug flags to see how new PCI devices on the Thunderbolt bus are added:
If you want to trace ACPI calls you can try using Open Core to override the DSDT with a version of the DSDT that has debug logging added to specific Thunderbolt related methods