To have a slide use the passthrough cameras for Augmented Reality, right click a scene and choose "AR_Passthrough" or add "_Passthrough" to the name of the scene.
Viewing Passthrough on Mirrored Desktop View:
To see the overlay of the real world with the mixed reality objects on the mirrored view for Meta headsets, download the Meta Quest Developer Hub for Windows. Once that is installed, login, connect the Meta Quest Pro and click "cast".