From the Sarna descriptions,
The Wolf Lancers are specifically freeborn and are noted as such specifically. Implying it's notable amongst the Steel Wolves.
The Wolf Trap Cluster/Crusaders Cluster doesn't say it's exclusively trueborn, but every CO and aide not only is trueborn but has a bloodname. Anastasia Kerensky, Jigme Connors, Maurice Radick.
And there's Kal Raddick, Varnoff Fetladral as bloodnameed trueborn. Katya Kerensky, Colten Fetladral, and Theuderic Carns.
With that number of known bloodnamed, there has to be a sizable number of trueborn without bloodnames yet?
Xera was not bloodnamed, but noted as being trueborn.