Honestly, it's all about how you frame your experiences. "I shadowed a MD who continued to explain to me the principles and tenants of osteopathic medicine. I have a few osteopathic shadowing opportunities lined up, but havent been able to yet due to helping impoverished children in the gaza strip with my magnanimous presence and altruism...." or something less lofty and crazy sounding.
It really is all about how they perceive you, not entirely about whats on paper. Getting you in the door for an interview is gonna depend on whats on paper: scores, LORs, etc. But if you are confident in your scores and application, I dont think its necessary to have shadowed a DO.
I personally never shadowed a DO, but I talked about how a DO physician aligned my ribs with HVLA. Good enough.