I adapted SSDT-TB3 Z270.aml for my Z170 with builtin TB3. When I have a look in ioreg, I see lots of extra PCI bridge stuff and no proper TB... I also see extra PCI devices(with the wrong names) in "About This Mac..."
Hot swap doesn't work, when I unplug my TB3 adapter my USB-C devices on the other (combo) port get kicked of too. Replugging doesn't do a thing.
Attached devices survive sleep, and I can shut my hack down without reboot.
OK. So after more play with the SSDT (copying so that device déclaration is almost identical to a real Mac pro) it now works with the THB cable disconnected. However, it doesn't work any differently than with it.
I've had hotplug working before, it just doesn't survive a sleep. And USB-c doesn't work better either.