Passthrough for Native C++ SDK

Hello,

Is there a passthrough API for the Oculus Platform SDK? From what I've seen, Meta doesn't seem to provide the passthrough data for privacy reasons. I'd like to do something similar as Unity where we create a composited image. Specifically compositing our application content on top of the passthrough but without using Unity/Unreal. I only want to use the native C++ SDK. 

If this isn't possible, is there a way we can use alpha blending with the passthrough image? Or is there a hardware setting we can modify that changes the opacity of the passthrough/running application?