"Yes, Libreboot says (or said) that it is is not possible run 3.0 (while
running free software), this is not true"
It is true: There is proprietary software running inside.
https://libreboot.org/faq/#firmware-usbhost
"I run my librebooted computer with gigabyte board and 4x3.0 usb ports PCI
card, and all my librebooted Thinkpads run 2x3.0-3x3.0 usb ports Express54
cards. And personally I send one card for Leah. These card are cheap (5-10€
for a unit), just plug it in (when computer is not powered on) and nothing
more."
Sure, but there is proprietary software running inside the card so what's on
the libreboot page is true: https://libreboot.org/faq/#firmware-usbhost
