Interesting question. Speaking from no experience (at least on US), my guess is no. Are you even able to associate your DM account with the buddy pass? The policy probably states somewhere that you can't, but I wouldn't be at all surprised if showing your card to a friendly agent did the trick.

I used a CO buddy pass a few months ago. I was never given an opportunity to enter my OnePass. Also, when the BP printed out, the PNR was printed in the area where my OnePass would go. Not sure if US does the same thing.