Hi @obey
Yes, you can still unlock the partition with a password (if you have setup one).
There is 2 possibilities:
1/ If the FIDO2 device PIN is not necessary to unlock the partition
Boot with no FIDO2 device plugged and after 30s seconds the system will try to ask a password
2/ If the FIDO2 device PIN is necessary to unlock the partition
Boot with no FIDO2 device plugged, type a PIN (any PIN but not an empty one) and after 30s seconds the system will try to ask a password
See FIDO2 fallback to password · Issue #19872 · systemd/systemd · GitHub