[tialaramex]

I don't run FreeBSD, so perhaps a FreeBSD user with a Yubikey will chime in, but as I understand it FreeBSD has Firefox and OpenSSH, and both these programs can use the FIDO feature (which is the focus of the article) on a USB Yubikey to authenticate you successfully to a remote system so it ought to work out of the box on up-to-date software.

The other features like using it to store PGP keys are a bit more fiddly to set going and you may need to read instructions specific to FreeBSD for those.