Hello, There are a couple of ways of using a yubikey as a certificate source for use with SSH. One is as a CCID device via PC/SC Lite and the other is via GPG. Going down the former approach, using PC/SC Lite to get setup from scratch (ignoring keygen), install pcsc-lite (as the middleware) and opensc (for the drivers). On NetBSD, as ukbd is attached to the yubikey, pcscd is unable to communicate with the device requiring a kernel built with device id hard-coded to attach to ugen. This doesn't seem to be an issue on FreeBSD (install pcsc-lite & opensc then off you go). I was wondering what the difference is in our USB stacks where pcscd can still communicate with the Yubikey without change?
I also stumbled across this old post which takes the approach of adding a new knobs so you can re-attach a device as ugen on the fly but I can't comment on the suitability. https://nonakap.hatenablog.com/entry/2015/12/24/000700 Sevan