This E3? Think you are getting ahead of yourself.
Tech demos are pointless, they are never even remotely representative. Rather they show something a bit more real and honest.
I expect announcements. Probably not a full on reveal, but Sony is already getting a lot of press and interest in the PS5. They will have to do something to keep some mindshare.
And I love tech demos. Obviously they don't typically indicate what you would see in games, but I really love them. Just raw demonstrations of what could be pushed out visually, or from a physics perspective. They can show games too, of course, but I like the spectacle.
I really liked that Lady Bug rendering demo they put out for the X too.