Is it possible to set up a Home Theatre with AirPlay 2

Using third party projector, with airplay 2, iPhone as media source and HomePod as speaker. I read home movie setup possible via airplay and no need Apple TV

everything recognises each other BUT although HomePod plays audio the picture is not of the moving movie - only a fixed picture advertising what’s playing on the HomePod ?

is this set up possible as a home theatre or must I buy another speaker ?

[Re-Titled by Moderator]