Pin object to Ortho Cam / back of user's phone

Options

Does anyone know how to pin/anchor a 3D object to the orthographic camera? Basically, I need to pin a 3D brick to the back of the user's phone.
This is for a game in Connected Lenses. The opponent should be able to see my brick, whereas I should be able to see through my brick (so it doesn't obstruct my view).
Is this possible? We've been searching for days for a solution, but this seems past Lens Studio's capabilities.

Side question... can we even make it landscape??

PS tags on forums is not working (admin)