Downgrade USB 3 to 2 inside the AppVM

I would like to force the use of USB2 from within one AppVM.
So the idea would be to do what’s describe in here , but not from Dom0, from the AppVM.
Is it possible?
I do not really get why in the AppVM the lspci command returns emply, whereas the lsusb does not. As a consequence, I can not set the setpci to the PCI device number.
Thank you for your help