I thought that it had all the same features, just not cloud sync. As far as I know the Yubikey is used for authenticating with their sync server. It doesn't actually help with the encryption
This is separate from having TOTP 2FA on the Bitwarden account itself, which is available on the free plan.[4]
[1] https://bitwarden.com/help/authenticator-keys/
[2] https://bitwarden.com/pricing/