Interesting. I went to check the stream and they go from GT7 trailer, to Ratchet trailer, to a short speech from someone at Insomniac (who does NOT mention wether the footage is in-game, in-engine or whatever) to some more footage. I might have missed so please kindly provide a timestamp for the statement.
I don't think YOU know how trailers are made: the moment devs were able to plug higher quality assets than possible, ramp up effects and then queue actions to be rendered by the engine offline like one renders a video, pre-release game footage became inmediatly suspect. It's like you live in a world were Andromeda, Anthem, The Witcher 3 or the bajillion times Ubi did it never happened. Here, you can have a look for yourself: https://www.youtube.com/results?search_query=video+game+downgrade
That's what you don't understand. You only need the most basic of support to use the real hardware to render out video. As soon as you get a dev environment up and running you can use the cinematic tools of your engine to throw in assets and then queue in actions to create believable video. At that point you don't need game logic, you don't need physics, you don't need anything else. It's like using your computer to render video: do you need any "game" to load up 3d assets animate them?
Why do you think companies keep coming up with terms like "in-engine", "in-game", "target gameplay", "representative gameplay" and so on? Because they can't say it's gameplay because it isn't.
Don't believe me? Go to youtube and search for "Unreal sequencer tutorial". Or if you want a past example from a Sony console announcement I think it was this Heavenly Sword trailer that famously was rendered at 1fps on a devkit.
Right at the start of the stream it states something like "all gameplay from this point forward is running on PlayStation 5 hardware"
From memory it's right before the Spider-Man trailer.