@DerTrickreiche:
What I found out ist, that it won't boot from a fresh copyed nanobsd-Image if there ist no USB-keyboard detected.
Hi Harry, thanks for the suggestion. I tried plugging an Apple USB keyboard into my pfSense box. The keyboard was detected, but pfSense still failed to boot with the same Root Mount Error:
Root mount waiting for: usbus4
Root mount waiting for: usbus4
Root mount waiting for: usbus4
uhub4: 8 ports with 8 removable, self powered
Root mount waiting for: usbus4
ugen4.2: <apple, inc.="">at usbus4
uhub5: <apple, 2="" 9="" inc.="" keyboard="" hub,="" class="" 0,="" rev="" 2.00="" 96.15,="" addr="">on usbus4
uhub5: 3 ports with 2 removable, bus powered
Root mount waiting for: usbus4
ugen4.3: <apple, inc="">at usbus4
Trying to mount root from ufs:/dev/ufs/pfsense0
ROOT MOUNT ERROR:</apple,></apple,></apple,>
Pete