Sony has now announced the small amount of PS4 games that will not work on the PS5 at launch. The list of games not compatible is only 10.
Sony has listed on the PlayStation Support page only 10 games that will not work on the PS5. The list of games have been posted down below.
-Afro Samurai 2 Revenge of Kuma Volume One
-TT Isle of Man – Ride on the Edge 2
-Just Deal With It!
-Shadow Complex Remastered
-Robinson: The Journey
-Hitman Go: Definitive Edition
It seems all PSVR games will still work on the PS5. Bear in mind you still need a PS camera to make it work. The PS5 camera will not work with PS4 VR games. You need a PS camera adapter too to connect it to PS5.
Other than that, a majority of over 4000 PS4 games will work on the PS5. You can either download the digital versions, or they can work using the physical discs.