On the note about backwards compatibility on PS5, at the beginning of October Sony actually announced that all but 10 games playable on PS4 will be playable on PS5, and then never spoke about it again. (
https://blog.playstation.com/2020/10/09/ps4-games-on-ps5-your-top-questions-answered/) So I'm only slightly surprised you guys are not aware. Not all games will be super-optimized, but like Xbox all games will make use of the better hardware.