Did disable system integrity protection (SIP) prior to installing the extension/driver?

Thanks for posting. I was scratching to my head as to why ssh with FIDO keys wasn't working with macOS Monterey 12.2 which ships with OpenSSH_8.6p1 (as you say, FIDO support has been present since openssh 8.2). Is Apple rolling their own implementation of OpenSSH? Back to installing OpenSSH with homebrew....